jpm training report
TRANSCRIPT
Page 1
JPM GROUP
JAY-USHIN LTD
GURGAON
SUMMER TRAINING REPORT
BY
MAYANK ASHOK BAFNA
MECHANICAL ENGINEERING
SURESH GYAN VIHAR UNIVERSITY
JAIPUR
Page 2
A TRAINING REPORT
INJECTION MOLDING
Submitted in partial fulfillment for the award of the degree of
BACHELOR OF TECHNOLOGY
In
MECHANICAL ENGINEERING
By
MAYANK ASHOK BAFNA
(ME10401206496)
SURESH GYAN VIHAR UNIVERSITY
MECHANICAL DEPARTMENT
Page 3
DECLARATION
I, MAYANK ASHOK BAFNA (ME10401206496),B.Tech(7th semester) of Suresh Gyan Vihar
University,Jaipur, hereby declare that the Summer Training Report entitled, “INJECTION MOLDING”, at
Jay Ushin Limited is an original work and the same has not been submitted to any other institute for the
award of any other degree.
A seminar presentation of the Training Report was made on ________________ and the suggestion as
approved by the faculty was duly incorporated.
Presentation-In-Charge Signature of the Candidate
Signature: ________________
Name of the Faculty: ________________
Page 4
ACKNOWLEDGEMENT
“If the words are symbol of undiluted feelings and token of gratitude then let the words play the
heralding role of expressing my feelings.”
Making a project is a result of meticulous efforts put in by many minds that contribute to the final report
formation. This is an honest effort towards putting forward whatever I have gained as a valuable
experience that will surely help me move up the learning curve towards the path I have chosen.
I am indeed thankful to honorable Dr. D.N. Rao, Former V.C, SGVU, Jaipur, who has provided the
wonderful opportunity of getting exposed to industrial and business working know-how. I extend my deepest
thank to my mentor and guide, Devesh Sharma, Senior Supervisor, JU-Shin,Gurgaon for giving me the
opportunity to understand the project and for providing me the necessary information whenever required.
I would like to render my sincere thanks to Mr. P.Ganguly, (HRD), Ms. Minakshi (HR),Mr. Manish
Sharma(Manager) , and Mr. Alok Sharma(Dept. Head,Tool Room) Jay Ushin Limited for their immense
encouragement, guidance and invaluable lecture sessions throughout my training. They all have been an
inspirational mentor guiding me through every step of my project, thus making the entire Project a complete
learning process.
Never the last, I would take the opportunity to thank to all the departmental heads of “JAY USHIN
LTD.” who gave their precious time in providing me with valuable information whenever needed.
Mayank Bafna
VII SEMESTER
Page 5
TRAINING SUMMARY
JAY-USHIN LTD a JPM Group Company is a joint venture firm with Ushin Ltd, Japan. It has a
name in the field of Original Equipment Manufacturing. After being established in 1986, in few
years it has developed a reputation of providing world class products with a technology to suit
Indian conditions. No doubt the policies and procedures followed by JU-Shin are of world
standards but with growing competition and to cut cost in this price competitive market scope of
improvement is always welcomed.
In my stint of training from 1st June 2015-30th June 2015.It was held at JPM Group Jay-Ushin
ltd, Gurgaon.The things, which I had read only in the books, were practically seen and
experienced in this memorable time span.
I was admitted to manufacturing plant in injection molding department, where OEM products
were produced first at raw condition.My mentor were Mr. Devesh Sharma, Senior Supervisor at
Jay-Ushin ltd, for the first 15 days I observed various products being manufactured at the plant
and the types of materials and machines used for it.Then I was shifted to Section-2 of Injection
Molding department, where vertical Injection molding Machines were used. My Training Project
was on Injection Molding, Defects and Use. I was introduced to various inspection
technologies to detect defects in molding and their prevention. I was also introduced to the
assembly line where Heater panel Assembly and Hazardous Switch assembly takes place.There
were 92 products to produce in the plant. During this project I learned a lot of things about the 5-
S rule, cause and effect analysis & counter measure, TPM (Total Productive Maintenance) etc.
which was very important from the industrial point of view. Apart from this I got the chance to
take part in extra activities, which goes side by side with the regular work. I also got the
opportunity to visit various other departments of assembly line and inspection department of the
company to know & understand how the final product was taking shape.
Page 6
INDEX
CHAPTER-1
INTRODUCTION
1.1 COMPANY INTRODUCTION
1.2 COMPANY HISTORY
1.3 REGIONAL HEADQUARTERS
1.4 JPM PRODUCTS
1.5 CUSTOMERS OF THE COMPANY
1.6 INTRODUCTION TO JU-SHIN PLANT
1.7 ORGANISATION AND EMPLOYEES
CHAPTER-2
PLANT LAYOUT AND WORKING STRUCTURE
2.1 JAY-USHIN PLANT LAYOUT
2.2 PLANT OVERVIEW
2.3 FLOW CHART
2.4 PRODUT RANGE
2.5 COMPANY VISION
CHAPTER-3
JU-SHIN PLANT
3.1 FEW OF THE IN-HOUSE FACILITIES
3.2 TOOL ROOM
Page 7
3.3 WAREHOUSE
3.4 INJECTION MOLDING MACHINE DEPARTMENT
3.5 ISPECTION ROOM
3.6 ASSEMBLY LINE
3.7 SAFETY USED WHILE WORKING IN JU-SHIN
3.8 JU-SHIN ENVIRONMENT POLICY
CHAPTER-4
INTRODUCTION TO INJECTION MOLDING DEPARTMENT
(MANUFACTURING)
4.1 INJECTION MOLDING DEPARTMENT
4.2 ORGANISATION STRUCTURE
4.3 INJECTION MOLDING DEPARTMENT STRUSTURE
CHAPTER-5
PRACTICAL TRAINING
5.1 TRAINING
5.2 PROJECT DURING TRAINING
5.2.1 PROCESS CHARACTERISTICS
5.2.2 MACHINERY & EQUIPMENT
5.2.3 PROCESS CYCLE
5.2.4 POWER REQUIREMENTS
5.2.5 INJECTION UNIT
5.2.6 CLAMPING UNIT
Page 8
5.2.7 LUBRICATION AND COOLING
5.2.8 MACHINE SPECIFICATIONS
5.2.9 TOOLING
5.2.10 MOLD BASE
5.2.11 MOLD CHANNELS
5.2.12 MOLD DESIGN
5.2.13 DESIGN RULES
5.2.14 MATERIALS
5.2.15 MOLDING DEFECTS
5.2.16 TOLERANCES AND SURFACES
5.3 ROLE DURING INDUSTRY TRAINING
CHAPTER-6
CONCLUSION
REFERENCES
BIBLIOGRAPHY
Page 9
CHAPTER - 1
INTRODUCTION
Page 10
1.1 COMPANY INTRODUCTION
JPM Group is a major entity on the corporate scene having diversified business interests in automotive
electrical and body parts, alternative fuels, energy, sponge iron, etc. The group is growing at a rapid pace
and is an industry leader in most parts manufactured by the group. Quality is the essence, and JPM Group,
have always stressed on the Customer Satisfaction. Consequently in this run for quality, quantity has
always pursued us. Group has ambitious plans to consolidate its position in India and abroad.
1.2 COMPANY HISTORY
In 1959, Shri J. P. Minda wondered why locksets and switches could not be made in India, when
he noticed the Indian Market Share of the same in the Global village. The envisaged idea started
taking shape to his idea by starting a locksets & switches unit. No one at that point of time
dreamt where this visionary would take this innovative beginning.
Then he thought to produce products like Key sets,switches, Heater Panels,Body Parts and
Today, the group is a multi-million, multi-location, multi-product business empire. Products are
Key sets, Switches, Instrument Clusters, Ignition Switches, Relays, Remote Keyless entry
systems, Body Parts, Batteries, Sponge Iron, Moulds, and Tools & Dies.
The group has recently ventured into Solar Power Generation and CNG Kits for automotive use.
The group has hundreds of vendors & associates, manufacturing parts as per our customer’s and
group’s specifications. The group has manufacturing facilities across India & globe.
Page 11
The core team of the group comprises the founder’s two sons, who are extending the legacy
forward and manage group companies:
Mr. Anil Minda
Mr. Ashwani Minda
Growth has been a way of life for the JPM Group. The group’s strength lies in its individual
companies with each one committed in consolidating its core strengths and excelling in its
chosen field.
The technology-driven group employs around 6,000 people across India. Over the years, Shri J.
P. Minda has built a reputation of integrity and dynamism with customers and his two sons are
continuing with his rich legacy.
1.3 REGIONAL HEADQUARTERS
Anu Industries Limited
Jay Ace Technologies Limited
Jay Auto Components Limited
Jay FE Cylinders Limited
Jay Iber Private Limited
Jay Iron & Steels Limited
Jay Nikki Industries Limited
Jay Ushin Limited
JNJ Electronics Limited
JNS Instruments Limited
JPM Automobiles Limited
JPM Tools Limited
Page 12
The Dots indicate the respective Headquarters
Page 13
1.4 JPM PRODUCTS
Various JPM Products are as follows:
1. AUTOMOTIVE 2. NON AUTOMOTIVE
a. Key Sets a. Gravity Die Casting
b. Body Parts b. Pressure Die Casting
c. Switches
d. Heater Control panel 3. ENERGY
e. Cap Noise Suppressors a. Batteries
f. Ignition Coil and Relays b. Solar Power
g. Security System
h. Washer Tank with Motors 4. STEEL
i. CNG Cylinders 5. TOOLS & DIES
Page 14
Page 15
1.5 CUSTOMERS OF THE COMPANY
TWO WHEELERS CUSTOMER
FOUR WHEELERS CUSTOMER
Page 16
1.6 INTRODUCTION TO JU-SHIN PLANT
Jay-Ushin Ltd. a JPM Group company was incorporated as a Joint Venture company with U-Shin Ltd,
Japan for manufacture of auto electrical, mechanical & electronic components for four wheelers in 1986.
It is a leading OEM manufacturer of automotive assemblies in India. Its products include lock sets,
latches, switches & body parts. The company is a major OE supplier to almost all makers of four wheeler
as well as two wheelers in India includes Maruti Suzuki Limited, Hyundai Motors India Ltd., General
Motors, Honda Siel, Honda Motor Cycle & Scooters Division, Mahindra & Mahindra and Tata Motors
Ltd..
U-Shin Ltd. engages in the design, development, manufacture, sale, and export of various system devices
and control machines for automotive, industrial machinery, and home security units. It also offers
mechanical, electrical systems, and components for automotive, industrial machinery, and home security
unit.
The company operates in three divisions: Automotive Parts, Industrial Equipments, and Home Security
Unit. The Automotive Parts division offers steering lock unit, lock sets, keyless entry, door latches, heater
control panels, door handles, switches, and sensors. The Industrial Equipments division provides
equipments for agricultural/constructive/industrial machines, equipments for telecommunication, meter
gauge for medical use, harness, cable wire, lump, operator's seat, electric fuel pump, electric measurement,
and communication device. The Home Security Unit division offers security system for home, hotel, and
office buildings; touch keys; handle sets; and electronic locks. The company, formerly known as
YUHSHIN SEIKI KOGYO CO., LTD., was founded in 1926 and is headquartered in Tokyo, Japan.
Page 17
JU-SHIN Plant Features are:
Plant Location-
Gurgaon,Haryan (1989)
Chennai,Tamil Nadu (1997)
Manesar, Haryana (2001)
No. of Employees at Plant- 1600
Facilities & Technologies
Product and Tool Design
Tool Room
Production Engineering
Die Casting Machines
Injection Molding Machines
Press Shop
Assembly
Test Lab
Products
•Security system - Key sets, Immobilizer, Keyless Entry, Remote Locking, etc.
•Switches - Combination switches, Panel switches, Handle Bar, Hazard Warning, Power Window, and
Defogger switches, Stop & Back-up Lamps, etc.
•Body Parts - Door Latches, Central Locking, Door Handles, Hood Latches, Striker, etc.
Page 18
1.7 ORGANISATION AND EMPLOYEES
MANAGEMENT STRUCTURE
J.P. Minda - Chairman
Ashwani Minda - Managing Director
Anil Minda - Technical Director
Shiv Raj Singh - Director
Ashok Panjwani - Director
Yukichi Harada - Director
Virendra kumar - Director
CHAIRMAN
MANAGING
DIRECTOR
JAY USHIN LTD
KEY SETS
COMBINATION & OTHER SW.
HEATER LEVER & PANEL
DOOR LATCHES
JNS INSTRUMENTS
LTD
INSTRUMENT CLUSTERS
SPEEDOMETERS
FUEL UNITS
SPEED SENSORS
JPM TOOLS LTD
MOULDING TOOLS
DIE CASTING TOOLS
STAMPING TOOLS
TECHNICAL
DIRECTOR
ANU INDUSTRIES LTD
IGNITION COILS & IGNITION WIRE SET
STARTER, WINKER,A/C FLASHER
WASHER MOTORS & RESERVOIRS
RELAY ASSEMBLY, CDI, ACTUATORS
NOISE SUPPRESSOR CAP
CENTRE DOOR LOCKING
Page 19
EQUITY SHARE
Minda family
U-shin
public
Page 20
CHAPTER-2
PLANT LAYOUT AND
WORKING STRUCTURE
Page 21
2.1 JAY-USHIN PLANT LAYOUT
Page 22
2.2 PLANT OVERVIEW
The Jay-Ushin Plant consist of 5 sections
Raw Material Storage House
Manufacturing section
Tool Room
Inspection Room
Assembly line
The manufacturing Plant consist of -
16 Horizontal Injection Molding Machine
6 Vertical Injection Molding Machine
4 Circular Rotating Disc Injection Molding Machine.
The No. of Employees engaged in manufacturing department are-50
Products made here are mainly parts of Heater Panels, locks, switches, knobs, pinions, key
assembler, Control Panel and other products upto a total of 92.
The leading customers for the products are:
Four Wheeler: Honda, Suzuki, Hyundai.
Two Wheeler: Hero, Honda, Yamaha.
Page 23
2.3 FLOW CHART
1. Customer’s Demand
2. Design of Product is made
3. Customer Feed back
4. Rapid Prototyping
5. Bulk production
6. Inspection
7. Asssembly
Flow chart
Page 24
2.4 PRODUT RANGE
JAY-USHIN PRODUCT RANGE
Lock set Scooter
Activa
Dio
Eterno
Aviator
Pleasure
Lock set Motor cycle
Unicorn
Shine
Stunner
Splendor
Heat
Zeus
Page 25
Switches Scooter
Active
Dio
Beat
Lead
Eterno
Aviator
Pleasure
Switches motor cycle
Unicorn
Shine
Stunner
Heat
Page 26
Zeus
Lock sets, Switches & Door latch-4 wheelers & 2 wheelers
Page 27
Power window switch
Mirror switch
Head lamp leveling switch
A/C Blower switch
Combination switch
HVAC Panel
Page 28
2.5 COMPANY VISION
Maintaining a global viewpoint, they are dedicated to supplying products of the
highest quality yet at a reasonable price for worldwide customer satisfaction.
JU-SHIN has a basic policy that is MSQCD. This basic policy has the following
description:
Fig: 2.11, Shows the Company vision
JU-Shin
Vision
Basic Policy
Promote People who
embody Ju-shin
Philosophy
Turn to Reality.
Indias No. 1 Green
Company in terms of
environment and
safety
To materialize quality
surpassing customers
/market expectation
Become a Benchmark
in OEM Products
A system which
cater the need of
market with
minimum
manufacturing lead
time
Page 29
CHAPTER-3
JU-SHIN PLANT
Page 30
3.1 FEW OF THE IN-HOUSE FACILITIES
High Pressure Die Casting, Gravity Die Casting & Low Pressure Die Casting Gravity Die-
Casting & Low pressure Die Casting Sections are for manufacturing critical parts.
3.2 TOOL ROOM
Lathe Machines, Drilling Machines and Grinding Machines are there for the finishing or
designing of Dummy Mould or to repair any wear in a part of Die.
Page 31
3.3 WAREHOUSE
It is the place where all the raw material used for molding plastic is stored.
The raw material is refilled daily in order to avoid down time.
3.4 INJECTION MOLDING MACHINE DEPARTMENT
An Injection molding machine, also known as an injection press, is a machine
for manufacturing plastic products by the injection molding process. It consists of
two main parts, an injection unit and a clamping unit.
The manufacturing department of the plant where raw material is put into hopper
and at certain temperature, injection of material takes place in Dies to form desired
product. After the production each product is inspected and marked OK by the
laborer for further assembly.
Page 32
Injection Molding Machine
3.5 ISPECTION ROOM
Before Assembly, the inspection of all the products manufactured, takes place here twice in
order to assure quality to the customer following company’s quality assurance policy.
Page 33
3.6 ASSEMBLY LINE
After final inspection, various products are shipped here, in order to assemble all the small parts
and create the major product like Heater Panels, Glass lenses, Hazardous Switches, Control
Switches etc.
Then the entire final product prepared are inspected once again and passed ahead
for shipping.
Page 34
3.7 SAFETY USED WHILE WORKING IN JU-SHIN
Various safety precautions used inside the plant are given below:
1. Proper maintenance of machine is made.
2. If barrel gets heated or mould is changed after 2-3 times, PURGE OUT is done.
3. Each mould is placed with the model on cover.
4. Heated Part is not allowed to touch and only technician inspect them.
5. mould is removed carefully, using gloves.
6. Default piece are removed before another molding.
3.8 JU-SHIN ENVIRONMENT POLICY
As responsible members of society and industry, we,Jay-Ushin Ltd,Gurgaon manufacturer of
OEM products, recognize that wellbeing of humans and conservation of earth’s environment is
important. By adopting Environment management system, JU-SHIN is fast moving towards
realization of JPM Green Factory Concept.
We shall endeavor to continually monitor, improve and conserve the environment in which we
operate. JU-SHIN is committed to achieve, environmental excellence in all its Industrial
activities, in the following ways:
Conserving environment through preventing pollution at its source of generation and
strengthening our existing pollution control system.
Promoting Conservation of resources such as energy, water, oil and grease and other Raw
materials, by reusing, recycling and minimizing the waste generation.
Complying with all applicable legal/ regulatory requirements and strive to go beyond
wherever possible.
JU-SHIN will continually improve its environmental management system following PDCA
Cycle to make it more effective. The Policy will be well disseminated to our employees as Well
as persons working on our behalf and to public at large.
Page 35
CHAPTER-4
INTRODUCTION
TO
INJECTION MOLDING
DEPARTMENT
(MANUFACTURING)
Page 36
4.1 INJECTION MOLDING DEPARTMENT
The activities of the Injection Molding department cover the entire process chain from the
original idea to the final product. In addition to thermoplastics and thermoplastic elastomers, the
department also covers thermosets, elastomers and polyurethanes.
Core competencies lie in the fields of:
Processing engineering
Mould technology
Mechanical engineering
Simulation
Plant organization
State-of-the-art equipment
JU-SHIN has a number of modern injection molding machines with clamping forces of between
60 and 200 tones. It also has a wide range of moulds, including simple geometries for analytical
testing, standard specimen geometries and complex practical geometries. It also has a large
selection of modern CAD/CAM/CAE tools for mould design and process simulation.
Necessity of Injection Molding
Injection molded components are consistently designed to minimize the design and
manufacturing information content of the enterprise system. There are three major benefits of the
process redesign effort.
First, closed loop pressure control has enabled tight coupling between the mass and momentum
equations
Second, the use of multiple melt actuators provides for the decoupling of melt pressures between
different locations in the mold cavity.
Third, the heat equation has been decoupled from the mass and momentum equations. This
allows the mold to be filled under isothermal conditions. Once the cavities are completely full
and attain the desired packing pressure, then the cooling is allowed to progress.
There are several factors that are critical to the injection molding process. These include:
1. Plastic Melt Temperatures 2. Barrel Temperatures
3. Nozzle Temperatures 4. Plastic Flow Rates
5. Plastic Pressure or Screw Back Pressure 6. Plastic Cooling Rates and Times
Page 37
4.2 ORGANISATION STRUCTURE
PRESIDENT AND
CEO
VICE PRESIDENT
PURCHASE SALES &
MARKETING
MANUFACTURING FINANCE &
ACCOUNT
ADMIN &
GENERAL
AFFAIR
OEM
MFG.
PPC PRODUCT
QUALITY
CONTROL
ERING
ENGINEERING
& DESIGN
INSPECTION
.
ASSEMBLY
GRAVITY
DIE CASTING
INJECTION
MOULDING
DEPARTMENT
Page 38
4.3 INJECTION MOLDING DEPARTMENT STRUSTURE
INJECTION MOULDING
MACHINE
HORIZONTAL
INJECTION
MOULDING
MACHINE
(250 tones)
For heavy
moulding
VERTICAL
INJECTION
MOULDING
MACHINE
(150 tones)
For light
moulding
CENTRE ROTATING
MOULDING
MACHINE
(250 tones)
For multiple
moulding in short
duration
Page 39
CHAPTER-5
PRACTICAL TRAINING
Page 40
5.1 TRAINING
My Training was held at manufacturing unit which was a injection molding department where
OEM Products were maufactured.There were two sections in the plant one was for horizontal
injection molding and the other was for vertical injection molding machine.
While the vertical machine was light in weight rating from 100-150 tonnes and were operated to
produce graded plastic product.
Horizontal machine was heavy upto 250 tonnes and were operated for hard plastic
products.Molding machine were mainly Single Molding and Multi molding machine which were
operated manually as well as automatically. During my training period some products which I
inspected and noticed were:
Heater Control Panels: These are control panel base in which the indicator,knobs and Wires are
after assembled.
Indicators: These are produced as four pice per press. These are natural in colour and usually
moulded automatically as defects are negligible according to industrial measures.
Pinions: These are white in colour produced to fit knobs on heater panel.
Some other products were Knobs, Switches, Lock Assembler , Automatic Buzz System etc.
Major Defects that were observed during the production of these products were:
Short shot-Caused due to generation of gas.
Color Streaks- caused due to thermal instability of colouring agent.
Weld Lines- it is a ‘V-shape’ defect formed during incomplete merging of
two separate parts.
Flash- formed due to increase in temperature during molding.
Stringiness- caused due to improrer surface of mould.
Page 41
Sink marks- hollow marks caused at small and delecate moulds
Silver Streaks- caused due to insufficient drying or degradation.
After three time inspection and rejection of defective pieces ,each package of products are
transported to the next line for assembling.
TOTAL PRODUCTIVE MAINTENANCE
TPM descends from Japan and came into existence in the seventies. After Dr W Edward Deming
made an impact in Japan through his teaching of quality, Japanese organization felt a need for
autonomous maintenance and small group activities to support the quality movement. Today
thousands of organizations all over the world are implementing TPM and about 100
organisations are now doing it in India.
Total productive maintenance (TPM) is a proven strategy for medium to large industries to get
superior business results and develop people skills to take on future business Challenges. Unlike
ISO certification process, in TPM, focus is on maintaining the equipment and process in perfect
condition- to get best quality products and involve all employees in Collectively carrying out loss
elimination, using analytical problem solving tools. The fundamental belief is that if the
equipment is maintained well and setting is done by a conscious, skilled operator, once can get
the best quality product. The whole concept of TPM is built around this belief and hence the
name total productive maintenance. However, this concept can be applied to places other than
plant and equipment and instead we could name Total productive Management rather than just
maintenance
Page 42
Some of the Priciples applied in the Industry were:
1. KAIZEN RULE-A Japanese term used in the business sense and applied to the workplace,
kaizen refers to activities that continually improve all functions and involve all employees from
the CEO to the assembly line workers. It also applies to processes, such as purchasing
and logistics, which cross organizational boundaries into supply chain
By improving standardized activities and processes, kaizen aims to eliminate waste Kaizen was
first implemented in several Japanese businesses after the Second World War, influenced in part
by American business and quality management teachers who visited the country. It has since
spread throughout the world and is now being implemented in environments outside of business
and productivity.
2. 5 S Rule
There are five 5S phases: They can be translated from the Japanese as "sort", "straighten",
"shine", "standardize", and "sustain". Other translations are possible.
Seiton Systematic Arrangement)
Can also be translated as "set in order", "straighten" or "streamline"
Arrange all necessary items so they can be easily selected for use
Seiri (Sort)
Remove unnecessary items and dispose them properly
Make work easier by eliminating obstacles
Seisou (Shine)
Can also be translated as "sweep", "sanitize", "shine", or "scrub"
Clean your workplace completely
Seiketsu (Standardize)
Page 43
Standardize the best practices in the work area.
Maintain high standards of housekeeping and workplace organization at all times.
Shitsuke (Sustain)
To keep in working order
Also translates as "do without being told" (though this doesn't begin with S).
Nakajima also known as the father of TPM, describes its concept in the following five points:
1. Maximize overall equipment efficiency
2. Establish through system of productive maintenance which involves maintenance prevention,
preventive maintenance and improvement related maintenance for the entire life cycle of the
equipment.
3. It is a team-based activity and requires participation of all departments.
4. Total employee involvement which involves all the employees from the top management to
the workers at shop floor.
5. It promotes and implements autonomous maintenance.
The above were the major information I came to learn during my training, while I also witnessed
the whole inspection process, setup and installation of Rotating Injection Molding Machine.
Some minor rules like below were also observed
Page 44
5.2 PROJECT DURING TRAINING
Injection molding is a manufacturing process for producing parts from both thermoplastic and
thermosetting plastic materials. Material is fed into a heated barrel, mixed, and forced into a
mold cavity where it cools and hardens to the configuration of the mold cavity. After a product is
designed, usually by an industrial designer or an engineer, molds are made by a mold maker (or
toolmaker) from metal, usually either steel or aluminum, and precision-machined to form the
features of the desired part. Injection molding is widely used for manufacturing a variety of
parts, from the smallest component to entire body panels of cars.
Fig. 1.2 Schematic Diagram of Plastic Injection molding
Page 45
5.2.1 PROCESS CHARACTERISTICS
Utilizes a ram or screw-type plunger to force molten plastic material into a mold cavity
Produces a solid or open-ended shape which has conformed to the contour of the mold
Uses thermoplastic or thermo set materials
Produces a parting line, sprue, and gate marks
Ejector pin marks are usually present
The plastic injection molding industry has evolved over the years from producing combs
and buttons to producing a vast array of products for many industries including automotive,
medical, aerospace, consumer products, toys, plumbing, packaging, and construction.
5.2.2 MACHINERY & EQUIPMENT
Injection molding machines consist of a material hopper, an injection ram or screw-type
plunger, and a heating unit. They are also known as presses, they hold the molds in which the
components are shaped. Presses are rated by tonnage, which expresses the amount of clamping
force that the machine can exert. This force keeps the mold closed during the injection process.
Tonnage can vary from less than 5 tons to 6000 tons, with the higher figures used in
comparatively few manufacturing operations.
The total clamp force needed is determined by the projected area of the part being
molded. This projected area is multiplied by a clamp force of from 2 to 8 tons for each square
inch of the projected areas. As a rule of thumb, 4 or 5 tons/in2 can be used for most products. If
the plastic material is very stiff, it will require more injection pressure to fill the mold, thus more
clamp tonnage to hold the mold closed. The required force can also be determined by the
material used and the size of the part, larger parts require higher clamping force.
Page 46
Fig.2.2 Injection Molding Machine.
Injection molding machines have many components and are available in different configurations,
including a horizontal configuration and a vertical configuration. However, regardless of their
design, all injection molding machines utilize a power source, injection unit, mold assembly, and
clamping unit to perform the four stages of the process cycle.
5.2.3 PROCESS CYCLE
The process cycle for injection molding is very short, typically between 2 seconds and 2 minutes,
and consists of the following four stages:
1. Clamping - Prior to the injection of the material into the mold, the two halves of the mold
must first be securely closed by the clamping unit. Each half of the mold is attached to the
injection molding machine and one half is allowed to slide. The hydraulically powered clamping
unit pushes the mold halves together and exerts sufficient force to keep the mold securely closed
while the material is injected. The time required to close and clamp the mold is dependent upon
the machine - larger machines (those with greater clamping forces) will require more time. This
time can be estimated from the dry cycle time of the machine.
Page 47
2. Injection - The raw plastic material, usually in the form of pellets, is fed into the injection
molding machine, and advanced towards the mold by the injection unit. During this process, the
material is melted by heat and pressure. The molten plastic is then injected into the mold very
quickly and the buildup of pressure packs and holds the material. The amount of material that is
injected is referred to as the shot. The injection time is difficult to calculate accurately due to the
complex and changing flow of the molten plastic into the mold. However, the injection time can
be estimated by the shot volume, injection pressure, and injection power.
3. Cooling - The molten plastic that is inside the mold begins to cool as soon as it makes contact
with the interior mold surfaces. As the plastic cools, it will solidify into the shape of the desired
part. However, during cooling some shrinkage of the part may occur. The packing of material in
the injection stage allows additional material to flow into the mold and reduce the amount of
visible shrinkage. The mold cannot be opened until the required cooling time has elapsed. The
cooling time can be estimated from several thermodynamic properties of the plastic and the
maximum wall thickness of the part.
4. Ejection - After sufficient time has passed, the cooled part may be ejected from the mold by
the ejection system, which is attached to the rear half of the mold. When the mold is opened, a
mechanism is used to push the part out of the mold. Force must be applied to eject the part
because during cooling the part shrinks and adheres to the mold. In order to facilitate the ejection
of the part, a mold release agent can be sprayed onto the surfaces of the mold cavity prior to
injection of the material. The time that is required to open the mold and eject the part can be
estimated from the dry cycle time of the machine and should include time for the part to fall free
of the mold. Once the part is ejected, the mold can be clamped shut for the next shot to be
injected.
Page 48
Fig.2.1 Injection molded part.
After the injection molding cycle, some post processing is typically required. During cooling, the
material in the channels of the mold will solidify attached to the part. This excess material, along
with any flash that has occurred, must be trimmed from the part, typically by using cutters. For
some types of material, such as thermoplastics, the scrap material that results from this trimming
can be recycled by being placed into a plastic grinder, also called regrind machines or
granulators, which regrinds the scrap material into pellets. Due to some degradation of the
material properties, the regrind must be mixed with raw material in the proper regrind ratio to be
reused in the injection molding process.
Page 49
5.2.4 POWER REQUIREMENTS
The power required for this process of injection molding depends on many things and
varies between materials used. Manufacturing Processes Reference Guide states that the power
requirements depend on "a material's specific gravity, melting point, thermal conductivity, part
size, and molding rate." Below is a table which best illustrates the characteristics relevant to the
power required for the most commonly used materials.
Material Specific Gravity Melting Point (°F)
Epoxy 1.12 to 1.24 248
Phenolic 1.34 to 1.95 248
Nylon 1.01 to 1.15 381 to 509
Polyethylene 0.91 to 0.965 230 to 243
Polystyrene 1.04 to 1.07 338
Table 1 Power Requirements.
5.2.5 INJECTION UNIT
The injection unit is responsible for both heating and injecting the material into the mold.
The first part of this unit is the hopper, a large container into which the raw plastic is poured. The
hopper has an open bottom, which allows the material to feed into the barrel. The barrel contains
the mechanism for heating and injecting the material into the mold. This mechanism is usually a
ram injector or a reciprocating screw. A ram injector forces the material forward through a
heated section with a ram or plunger that is usually hydraulically powered. Today, the more
common technique is the use of a reciprocating screw. A reciprocating screw moves the material
forward by both rotating and sliding axially, being powered by either a hydraulic or electric
motor.
Page 50
The material enters the grooves of the screw from the hopper and is advanced towards the
mold as the screw rotates. While it is advanced, the material is melted by pressure, friction, and
additional heaters that surround the reciprocating screw. The molten plastic is then injected very
quickly into the mold through the nozzle at the end of the barrel by the buildup of pressure and
the forward action of the screw. This increasing pressure allows the material to be packed and
forcibly held in the mold. Once the material has solidified inside the mold, the screw can retract
and fill with more material for the next shot.
Fig.2.3 Injection molding machine - Injection unit.
5.2.6 CLAMPING UNIT
Prior to the injection of the molten plastic into the mold, the two halves of the mold must
first be securely closed by the clamping unit. When the mold is attached to the injection molding
machine, each half is fixed to a large plate, called a platen. The front half of the mold, called the
mold cavity, is mounted to a stationary platen and aligns with the nozzle of the injection unit.
The rear half of the mold, called the mold core, is mounted to a movable platen, which slides
along the tie bars. The hydraulically powered clamping motor actuates clamping bars that push
Page 51
the moveable platen towards the stationary platen and exert sufficient force to keep the mold
securely closed while the material is injected and subsequently cools. After the required cooling
time, the mold is then opened by the clamping motor. An ejection system, which is attached to
the rear half of the mold, is actuated by the ejector bar and pushes the solidified part out of the
open cavity.
Fig.2.4 Injection molding machine - Clamping unit.
5.2.7 LUBRICATION AND COOLING
Obviously, the mold must be cooled in order for the production to take place. Because of
the heat capacity, inexpensiveness, and availability of water, water is used as the primary cooling
agent. To cool the mold, water can be channeled through the mold to account for quick cooling
times. Usually a colder mold is more efficient because this allows for faster cycle times.
However, this is not always true because crystalline materials require the opposite: a warmer
mold and lengthier cycle time.
Page 52
5.2.8 MACHINE SPECIFICATIONS
Injection molding machines are typically characterized by the tonnage of the clamp force
they provide. The required clamp force is determined by the projected area of the parts in the
mold and the pressure with which the material is injected. Therefore, a larger part will require a
larger clamping force. Also, certain materials that require high injection pressures may require
higher tonnage machines. The size of the part must also comply with other machine
specifications, such as shot capacity, clamp stroke, minimum mold thickness, and platen size.
5.2.9 TOOLING
The injection molding process uses molds, typically made of steel or aluminum, as the
custom tooling. The mold has many components, but can be split into two halves. Each half is
attached inside the injection molding machine and the rear half is allowed to slide so that the
mold can be opened and closed along the mold's parting line. The two main components of the
mold are the mold core and the mold cavity. When the mold is closed, the space between the
mold core and the mold cavity forms the part cavity, that will be filled with molten plastic to
create the desired part. Multiple-cavity molds are sometimes used, in which the two mold halves
form several identical part cavities.
5.2.10 MOLD BASE
The mold core and mold cavity are each mounted to the mold base, which is then fixed to
the platens inside the injection molding machine. The front half of the mold base includes a
support plate, to which the mold cavity is attached, the sprue bushing, into which the material
will flow from the nozzle, and a locating ring, in order to align the mold base with the nozzle.
The rear half of the mold base includes the ejection system, to which the mold core is attached,
and a support plate. When the clamping unit separates the mold halves, the ejector bar actuates
Page 53
the ejection system. The ejector bar pushes the ejector plate forward inside the ejector box,
which in turn pushes the ejector pins into the molded part. The ejector pins push the solidified
part out of the open mold cavity.
Fig.2.7 Mold base.
5.2.11 MOLD CHANNELS
In order for the molten plastic to flow into the mold cavities, several channels are
integrated into the mold design. First, the molten plastic enters the mold through the sprue.
Additional channels, called runners, carry the molten plastic from the sprue to all of the cavities
that must be filled. At the end of each runner, the molten plastic enters the cavity through a gate
which directs the flow. The molten plastic that solidifies inside these runners is attached to the
part and must be separated after the part has been ejected from the mold. However, sometimes
Page 54
hot runner systems are used which independently heat the channels, allowing the contained
material to be melted and detached from the part. Another type of channel that is built into the
mold is cooling channels. These channels allow water to flow through the mold walls, adjacent
to the cavity, and cool the molten plastic.
Fig.2.8 Mold channels.
5.2.12 MOLD DESIGN
In addition to runners and gates, there are many other design issues that must be
considered in the design of the molds. Firstly, the mold must allow the molten plastic to flow
easily into all of the cavities. Equally important is the removal of the solidified part from the
mold, so a draft angle must be applied to the mold walls. The design of the mold must also
accommodate any complex features on the part, such as undercuts or threads, which will require
additional mold pieces. Most of these devices slide into the part cavity through the side of the
Page 55
mold, and are therefore known as slides, or side-actions. The most common type of side-action is
a side-core which enables an external undercut to be molded. Other devices enter through the end
of the mold along the parting direction, such as internal core lifters, which can form an internal
undercut. To mold threads into the part, an unscrewing device is needed, which can rotate out of
the mold after the threads have been formed.
Fig.3.1 Mold – Closed.
Page 56
Fig.3.2 Mold - Exploded view.
Fig.3.3 Standard two plates tooling – core and cavity are inserts in a mold base – "Family mold" of 5 different parts.
The mold consists of two primary components, the injection mold (A plate) and the
ejector mold (B plate). Plastic resin enters the mold through a sprue in the injection mold, the
sprue bushing is to seal tightly against the nozzle of the injection barrel of the molding machine
and to allow molten plastic to flow from the barrel into the mold, also known as cavity. The
Page 57
sprue bushing directs the molten plastic to the cavity images through channels that are machined
into the faces of the A and B plates. These channels allow plastic to run along them, so they are
referred to as runners. The molten plastic flows through the runner and enters one or more
specialized gates and into the cavity geometry to form the desired part.
The amount of resin required to fill the sprue, runner and cavities of a mold is a shot.
Trapped air in the mold can escape through air vents that are ground into the parting line of the
mold. If the trapped air is not allowed to escape, it is compressed by the pressure of the incoming
material and is squeezed into the corners of the cavity, where it prevents filling and causes other
defects as well. The air can become so compressed that it ignites and burns the surrounding
plastic material. To allow for removal of the molded part from the mold, the mold features must
not overhang one another in the direction that the mold opens, unless parts of the mold are
designed to move from between such overhangs when the mold opens (utilizing components
called Lifters).
Sides of the part that appear parallel with the direction of draw (The axis of the cored
position (hole) or insert is parallel to the up and down movement of the mold as it opens and
closes) are typically angled slightly with (draft) to ease release of the part from the mold.
Insufficient draft can cause deformation or damage. The draft required for mold release is
primarily dependent on the depth of the cavity: the deeper the cavity, the more draft necessary.
Shrinkage must also be taken into account when determining the draft required. If the skin is too
thin, then the molded part will tend to shrink onto the cores that form them while cooling, and
cling to those cores or part may warp, twist, blister or crack when the cavity is pulled away.
The mold is usually designed so that the molded part reliably remains on the ejector (B)
side of the mold when it opens, and draws the runner and the sprue out of the (A) side along with
the parts. The part then falls freely when ejected from the (B) side. Tunnel gates, also known as
submarine or mold gate, is located below the parting line or mold surface. The opening is
machined into the surface of the mold on the parting line. The molded part is cut (by the mold)
from the runner system on ejection from the mold. Ejector pins, also known as knockout pin, is a
Page 58
circular pin placed in either half of the mold (usually the ejector half) which pushes the finished
molded product, or runner system out of a mold.
The standard method of cooling is passing a coolant (usually water) through a series of holes
drilled through the mold plates and connected by hoses to form a continuous pathway. The
coolant absorbs heat from the mold (which has absorbed heat from the hot plastic) and keeps the
mold at a proper temperature to solidify the plastic at the most efficient rate.
To ease maintenance and venting, cavities and cores are divided into pieces, called inserts, and
sub-assemblies, also called inserts, blocks, or chase blocks. By substituting interchangeable
inserts, one mold may make several variations of the same part.
More complex parts are formed using more complex molds. These may have sections called
slides that move into a cavity perpendicular to the draw direction, to form overhanging part
features. When the mold is opened, the slides are pulled away from the plastic part by using
stationary “angle pins” on the stationary mold half. These pins enter a slot in the slides and cause
the slides to move backward when the moving half of the mold opens. The part is then ejected
and the mold closes. The closing action of the mold causes the slides to move forward along the
angle pins.
Some molds allow previously molded parts to be reinserted to allow a new plastic layer
to form around the first part. This is often referred to as over molding. This system can allow for
production of one-piece tires and wheels.This process is actually an injection molding process
performed twice. In the first step, the base color material is molded into a basic shape. Then the
second material is injection-molded into the remaining open spaces. That space is then filled
during the second injection step with a material of a different color.
A mold can produce several copies of the same parts in a single "shot". The number of
"impressions" in the mold of that part is often incorrectly referred to as cavitations. A tool with
one impression will often be called a single impression (cavity) mold.Some extremely high
production volume molds (like those for bottle caps) can have over 128 cavities. In some cases
Page 59
multiple cavity tooling will mold a series of different parts in the same tool. Some toolmakers
call these molds family molds as all the parts are related.
5.2.13 DESIGN RULES
1.1 MAXIMUM WALL THICKNESS:
Decrease the maximum wall thickness of a part to shorten the cycle time (injection time and
cooling time specifically) and reduce the part volume
INCORRECT
Part with thick walls
CORRECT
Part redesigned with thin walls
Uniform wall thickness will ensure uniform cooling and reduce defects
INCORRECT
CORRECT
Page 60
Non-uniform wall thickness (t1 ≠ t2) Uniform wall thickness (t1 = t2)
1.2 CORNERS:
Round corners to reduce stress concentrations and fracture
Inner radius should be at least the thickness of the walls
INCORRECT
Sharp corner
CORRECT
Rounded corner
1.3 DRAFT:
Apply a draft angle of 1° - 2° to all walls parallel to the parting direction to facilitate removing
the part from the mold.
INCORRECT
No draft angle
CORRECT
Page 61
1.4 RIBS:
Add ribs for structural support, rather than increasing the wall thickness
INCORRECT
Thick wall of thickness t
CORRECT
Thin wall of thickness t with ribs
Orient ribs perpendicular to the axis about which bending may occur
INCORRECT
Incorrect rib direction under load F
CORRECT
Correct rib direction under load F
Thickness of ribs should be 50-60% of the walls to which they are attached
Height of ribs should be less than three times the wall thickness
Round the corners at the point of attachment
Apply a draft angle of at least 0.25°
Page 62
INCORRECT
Thick rib of thickness t
CORRECT
Thin rib of thickness t
Close up of ribs
1.5 BOSSES:
Wall thickness of bosses should be no more than 60% of the main wall thickness
Radius at the base should be at least 25% of the main wall thickness
Should be supported by ribs that connect to adjacent walls or by gussets at the base.
INCORRECT
Isolated boss
CORRECT
Isolated boss with ribs (left) or gussets (right)
If a boss must be placed near a corner, it should be isolated using ribs.
Page 63
INCORRECT
Boss in corner
CORRECT
Ribbed boss in corner
1.6 UNDERCUTS:
Minimize the number of external undercuts
o External undercuts require side-cores which add to the tooling cost
o Some simple external undercuts can be molded by relocating the parting line
Simple external undercut
Mold cannot separate
New parting line allows
undercut
o Redesigning a feature can remove an external undercut
Page 64
Part with hinge Hinge requires side-core
Redesigned hinge
New hinge can be molded
Minimize the number of internal undercuts
o Internal undercuts often require internal core lifters which add to the tooling cost
o Designing an opening in the side of a part can allow a side-core to form an internal
undercut
Internal undercut accessible from the side
o Redesigning a part can remove an internal undercut
Page 65
Part with internal undercut
Mold cannot separate
Part redesigned with slot
New part can be molded
Minimize number of side-action directions
o Additional side-action directions will limit the number of possible cavities in the mold
5.2.14 MATERIALS
There are many types of materials that may be used in the injection molding process. Most
polymers may be used, including all thermoplastics, some thermosets, and some elastomers.
When these materials are used in the injection molding process, their raw form is usually small
pellets or a fine powder. Also, colorants may be added in the process to control the color of the
final part. The selection of a material for creating injection molded parts is not solely based upon
the desired characteristics of the final part. While each material has different properties that will
affect the strength and function of the final part, these properties also dictate the parameters used
in processing these materials. Each material requires a different set of processing parameters in
Page 66
the injection molding process, including the injection temperature, injection pressure, mold
temperature, ejection temperature, and cycle time. A comparison of some commonly used
materials is shown below (Follow the links to search the material library).
Material name
Abbreviation
Trade names
Description
Applications
Acetal POM Celcon, Delrin,
Hostaform,
Lucel
Strong, rigid,
excellent fatigue
resistance,
excellent creep
resistance.
Bearings, cams,
gears, handles,
plumbing
components,
rollers, rotors,
slide guides,
valves
Acrylic PMMA Diakon,
Oroglas, Lucite,
Plexiglas
Rigid, brittle,
scratch resistant,
transparent,
optical clarity,
low/medium
cost.
Display stands,
knobs, lenses,
light housings,
panels,
reflectors, signs,
shelves, trays
Acrylonitrile
Butadiene Styrene
ABS Cycolac,
Magnum,
Novodur,
Terluran
Strong, flexible,
low mold
shrinkage (tight
tolerances),
chemical
resistance,
electroplating
capability,
naturally
opaque,
low/medium
cost
Automotive
(consoles,
panels, trim,
vents), boxes,
gauges,
housings,
inhalors, toys
Cellulose Acetate CA Dexel, Cellidor, Tough, Handles,
Page 67
Setilithe transparent, high
cost
eyeglass frames
Polyamide 6 (Nylon) PA6 Akulon,
Ultramid, Grilon
High strength,
fatigue
resistance,
chemical
resistance, low
creep, low
friction, almost
opaque/white,
medium/high
cost
Bearings,
bushings, gears,
rollers, wheels
Polyamide 6/6
(Nylon)
PA6/6 Kopa, Zytel,
Radilon
High strength,
fatigue
resistance,
chemical
resistance, low
creep, low
friction, almost
opaque/white,
medium/high
cost
Handles, levers,
small housings,
zip ties
Polycarbonate PC Calibre, Lexan,
Makrolon
Very tough,
temperature
resistance,
dimensional
stability,
transparent, high
cost
Automotive
(panels, lenses,
consoles),
bottles,
containers,
housings, light
covers,
reflectors, safety
helmets and
shields
Polyester -
Thermoplastic
PBT, PET Celanex,
Crastin, Lupox,
Rynite, Valox
Rigid, heat
resistance,
chemical
Automotive
(filters, handles,
pumps),
Page 68
resistance,
medium/high
cost
bearings, cams,
electrical
components
(connectors,
sensors), gears,
housings,
rollers,
switches, valves
Polyphenylene
Oxide
PPO Noryl,
Thermocomp,
Vamporan
Tough, heat
resistance, flame
resistance,
dimensional
stability, low
water
absorption,
electroplating
capability, high
cost
Automotive
(housings,
panels),
electrical
components,
housings,
plumbing
components
Polyphenylene
Sulphide
PPS Ryton, Fortron Very high
strength,heat
resistance,very
high cost
switches, and
shields
Table 3: Materials.
Page 69
5.2.15 MOLDING DEFECTS
Injection molding is a complex technology with possible production problems. They can either
be caused by defects in the molds or more often by part processing (molding)
Molding
Defects
Alternative
Name
Descriptions Causes
Blister Blistering Raised or layered
zone on surface of
the part
Tool or material is too hot, often caused
by a lack of cooling around the tool or a
faulty heater
Burn marks Air Burn/
Gas Burn/
Dieseling
Black or brown
burnt areas on the
part located at
furthest points from
gate or where air is
trapped
Tool lacks venting, injection speed is too
high
Color streaks
(US)
Colour
streaks (UK)
Localized change of
color/colour
Masterbatch isn't mixing properly, or the
material has run out and it's starting to
come through as natural only. Previous
colored material "dragging" in nozzle or
check valve.
Delamination Thin mica like
layers formed in
part wall
Contamination of the material e.g. PP
mixed with ABS, very dangerous if the
part is being used for a safety critical
application as the material has very little
strength when delaminated as the
materials cannot bond
Flash Burrs Excess material in
thin layer exceeding
normal part
High injection speed/material injected,
clamping force too low. Can also be
caused by dirt and contaminants around
Page 70
geometry tooling surfaces.
Flow marks Flow lines Directionally "off
tone" wavy lines or
patterns
Injection speeds too slow (the plastic has
cooled down too much during injection,
injection speeds must be set as fast as
you can get away with at all times)
Jetting Deformed part by
turbulent flow of
material
Poor tool design, gate position or runner.
Injection speed set too high.
Knit Lines Weld lines Small lines on the
backside of core
pins or windows in
parts that look like
just lines.
Caused by the melt-front flowing around
an object standing proud in a plastic part
as well as at the end of fill where the
melt-front comes together again. Can be
minimized or eliminated with a mold-
flow study when the mold is in design
phase. Once the mold is made and the
gate is placed one can only minimize this
flaw by changing the melt and the mold
temperature.
Polymer
degradation
polymer breakdown
from hydrolysis,
oxidation etc.
Excess water in the granules, excessive
temperatures in barrel
Sink marks [sinks] Localized
depression (In
thicker zones)
Holding time/pressure too low, cooling
time too short, with sprueless hot runners
this can also be caused by the gate
temperature being set too high. Excessive
material or thick wall thickness.
Short shot Non-fill /
Short mold
Partial part Lack of material, injection speed or
pressure too low, mold too cold
Splay marks Splash mark / Circular pattern Moisture in the material, usually when
Page 71
Silver streaks around gate caused
by hot gas
hygroscopic resins are dried improperly.
Trapping of gas in "rib" areas due to
excessive injection velocity in these
areas. Material too hot.
Stringiness Stringing String like remain
from previous shot
transfer in new shot
Nozzle temperature too high. Gate hasn't
frozen off
Voids Empty space within
part (Air pocket)
Lack of holding pressure (holding
pressure is used to pack out the part
during the holding time). Filling to fast,
not allowing the edges of the part to set
up. Also mold may be out of registration
(when the two halves don't center
properly and part walls are not the same
thickness).
Weld line Knit line /
Meld line /
Transfer line
Discolored line
where two flow
fronts meet
Mold/material temperatures set too low
(the material is cold when they meet, so
they don't bond). Point between injection
and transfer (to packing and holding) too
early.
Warping Twisting Distorted part Cooling is too short, material is too hot,
lack of cooling around the tool, incorrect
water temperatures (the parts bow
inwards towards the hot side of the tool)
Uneven shrinking between areas of the
part
Table 4: Molding Defects.
Page 72
5.2.16 TOLERANCES AND SURFACES
Molding tolerance is a specified allowance on the deviation in parameters such as
dimensions, weights, shapes, or angles, etc. To maximize control in setting tolerances there is
usually a minimum and maximum limit on thickness, based on the process used.[36] Injection
molding typically is capable of tolerances equivalent to an IT Grade of about 9–14. The possible
tolerance of a thermoplastic or a thermoset is ±0.008 to ±0.002 inches. Surface finishes of two to
four micro inches or better are can be obtained. Rough or pebbled surfaces are also possible.
Molding Type Typical Possible
Thermoplastic ±0.008 ±0.002
Thermoset ±0.008 ±0.002
Table 5: Tolerances.
Page 73
5.3 ROLE DURING INDUSTRY TRAINING
As an Intern I had two major roles in my industry training:
Trainee- As a trainee I was required to learn and understand all the pros and cons of indutry and
its manufacturing unit.I was admitted to manufacturing department where I learnt about Injection
Molding Machine. I also learned
To operate molding machine
To handle human resource at industry and how to manage the labour
I learnt about the Dies used for Molding
various materials used for Molding
Precautions to be taken while operating in a industry
How the machine and management works
Total Productive Management
Junior Supervisor- The role is traditionally a difficult one. You must fulfill various
responsibilities to your employees, work group and organization. You also are responsible for
ensuring the work is carried out in such a way that no one's security, safety or health is
jeopardized. We used to help the labor to control the machine and program the machine for
molding, we were also asked to watch the performance of the machine and determine OEE
(overall effective efficiency).If any maintenance proplem occurred during molding, we had to
contact the senior supervisor or our mentor
Page 74
CHAPTER-6
CONCLUSION
“I hear and I forget. I see and I remember. I do and I understand.” – Confucius
Training develops students’ professional and practical skills, encouraging them to apply skills
and knowledge acquired through study in a real-life environment. Students are placed with an
employer to work on a research project or undertake work experience under the guidance of
industry and academic supervision.
Training is a key factor in enhancing the efficiency and expertise of the workforce. The Students
Work Experience program prepares students for labor markets. It has become an innovative
phenomenon in human resources development and training in India. Increased specialization of
skills means that the term “profession” is now used for certain occupations which enjoy prestige
and which give esoteric service. Such professions include architects, surveyors, doctors,
librarians and information scientists, and engineers, among others.
It helped to understand various norms of industries. Provided an intellectual increase regarding
manufacturing and production.
Page 75
REFERENCES
1. Dr. Mukherjee
2. Mr. Devesh Sharma
3. Mr. Manish
4. Mr. Rahul Pathak
BIBLIOGRAPHY
1. Jpmgroup.co.in
2. Jay Ushin LTD
3. Wikipedia-Production
4. Google.com