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Design and development of Foot operated sanitizer to combat Covid-19 pandemic and post pandemic period

A. S. Sekhar1*

1Professor, Department of Mechanical Engineering, and Professor in-charge, Central Workshop Indian Institute of Technology Madras, Chennai, India

G. Balaganesan2, N. T. Sasikumar2, R. Pazhanivel2, T. Balamurugan2,

S. Chellapandian2, Dillibabu2, K. Kumar2 and S. Praveen2 2 Central Workshop

Indian Institute of Technology Madras, Chennai, India

*Corresponding author: as_sekhar@iitm.ac.in Abstract

The devices such as Intubation box, ventilators, masks, touch-less sanitizers etc., are the neediest products during Covid-19 pandemic and some are post pandemic period also. Touch-less sensing products are expensive and it might not be possible for firms to implement them in all aspects. This paper discusses various stages of design, selection of material for cost effective design, arriving manufacturing processes of a foot operated sanitizer based on availability of limited resources in an academic Institution. Function structure is developed which resulted into a modular design of this unit. The dispensing unit developed in this study is able to actuate a vertical plunger type 500 ml sanitizer/liquid soap dispensers. Value analysis has been carried out to optimize the cost and functionality of dispensing unit. The pedal to actuate the device is ergonomically positioned. Each part in the product is modeled and analysed using a software tool to find the stresses and deformations. Fatigue tests are also carried out in this study to assess durability and performance of the product.

Key words: Covid 19; devices; product design; foot operated; sanitizer; dispenser.

1. Introduction

The world is taking all necessary steps to ensure that we are prepared well to face the challenge and threat posed by the growing pandemic of COVID-19 the Corona Virus. With active support of the people across globe, the spread of the Virus is contained in every country. The most important factor in preventing the spread of the Virus locally is to empower the citizens with the right information and taking precautions as per the advisories being issued by the Government. Research and development institutes have come forward to develop the medicine, medical equipment to meet the demand, PPE to the medical and frontline workers and public of respective countries. The mode for spread of Covid 19 virus is through air and surfaces which are exposed

ISME Journal of Mechanics and Design, Special Issue

Vol. 4, No. 2, 2020 pp. 1-17

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during the presence of affected patients. Isolation from the affected patient is best way to avoid virus pickup. The prevention of virus pickup through surfaces can be done through touch contacts. There is a need to touch various common utilities in day to day in an office, home and public places Touch less technology is to stay and will witness the growth much faster than earlier period due to the COVID-19 outbreak. Experts point out that touch-less technology is likely to accelerate implementation in the devices which are accessed by a group and large group of people. Cost of sensors is a challenge. Touch-less sensing products are expensive and it might not be possible for firms to implement them in all aspects. In Wipro, Bangalore, India washrooms are fitted with sensors to disperse water [1]. An analyst pointed out that, firms cannot make the entire office premises touchless given how expensive it would be at a time when businesses are hit [1]. While wider adoption might bring prices down, firms will be judicious, the analyst added. Mechanical actuated devices are remedial options for replacement of expensive touchless technology using electronics. With the worldwide COVID-19 crisis keeping everyone confined to their homes, more people than ever are spending hours upon hours in front of their computers. And, while this “new normal” continues, product development teams from designers to marketers have the ability to find out about customer attitudes to help create a roadmap that will guide new product innovations or enhancement along with exploring ways to improve systems for the supply chain[2].

The IT systems and remote collaboration tools are already well established and practiced, and have enabled the team to seamlessly make the transition to working from home. A few remain in project laboratories, practicing appropriate isolation rules, continuing project work that cannot leave the office. . Academicians and Researchers have come forward to contribute on product development to meet challenges during pandemic period. Ideas and concepts are being shared across the network. Our designers and engineers have been motivated to contribute solutions to help with distributing potentially life-saving technological ideas such as fast-to-market ventilators, or helping productize and productionise personal protective equipment (PPE) ideas being designed and trialed by medical professionals around the world [3].

The Defence Research & Development Organisation (DRDO), India has announced a few more products made by its scientists with indigenous technologies to combat coronavirus pandemic. The devices are Automatic Hand Sanitizer Dispensing Unit, Hand Surface Sanitizers, UV Based Disinfection Devices, Personnel Vehicle Area Sanitization Equipment, Sample Collection Enclosures, Hospital Aids, Mobile Labs, PPE, and Miscellaneous[4-6]. Designs, such as foot-operated doorknobs, could have a genuine shelf-life in a world whose attitude to hand hygiene may be permanently altered. In the present study, the design and development of a foot-operated sanitizer dispensing unit has been carried out using the product design principles.

2. Product Development approaches

The product development process encompasses all steps needed to take a product from concept to market availability [7]. This includes identifying a market need, researching the competitive landscape, conceptualizing a solution, developing a product roadmap, building a minimum viable product, etc. Product development also requires the effort and input from various stake holders who are involved in various stages of product design, prototyping, manufacturing and end use. There are several well known systems for new product development. Rapid development approach is discussed in this paper. Design thinking is a framework for developing new products based on first identifying a problem or need from the user’s perspective [8].

This approach is generally used to develop physical products as opposed to digital products like software. There are many variations to the new product development process. Some organizations use a five-step approach as shown in figure 1, while others break it into as many as eight stages. Although their specific approaches vary, most companies that repeatedly deliver successful products to market share certain strategies. Table 1 shows some of the best practices for new product development. Rapid product development (RPD) is a holistic product development concept that describes a rapid development process achieved mainly by combining and integrating innovative prototyping technologies as well as modern tools into the research and development process. The primary objectives of RPD are to shorten the time to launch of product from the

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first sketch to application by users, to develop innovative products by optimizing the factors time, costs and quality.

Fig. 1: Design thinking 5 steps approach in product development

Table 1. Rational product management and development

Steps Stage Activity I Start User needs and finding frustrations in users mind

II Market Research To find vacuum in market III Communication Regularly across company, sharing knowledge and insights

IV Product

development Assigning one of the available frameworks for product development process

V Validation Conceptual validation through ‘soft launch’ to test with a small group of users

VI Ideation and brainstorming

Cross functional team can be involved to find insights

VII Realistic product development

Within timelines using resources and expertise within organization

3. Design Philosophy & Concept Development

3.1 Need Analysis / market The primary objective of product development during pandemic period is to meet the requirements of covid

patients, medical practitioners and public population. User-needs analysis is important because the interface design will be based on this information. Faulty assumptions or goals (about users) will lead to a faulty design that is difficult to fix once in place. The need analysis of the product is to define the audience, identify user goals,

Empathize with users

Define the problem

Brainstorming for potential solutions

Prototype building

Testing the solution

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set usability objectives, identify design constraints and define functional specifications. The methodology is to identify a user needs and surveys. The need of a product and design is possible by three ways, the first one is the need of a client, and the second is modification of existing product to meet the customer requirement, the third is generation of a new product. Table 2 provides the need analysis of the product during pandemic period to encounter the Covid 19 patients by medical teams, maintaining social distancing and touch- less operation in various gadgets used in day to day life to prevent picking-up virus. The foot operated sanitizer dispensing device market can be segmented based on type, capacity, operation mode, end-use, distribution channel, and geography. Based on type, the market can be classified into gel hand sanitizer dispensing machines, liquid hand sanitizer dispensing devices, foam hand sanitizer dispensing devices, and others. Based on end use, the foot operated sanitizer market can be divided into health care, coffee shops, colleges & universities, schools, shopping complexes, subway stations, hotels & restaurants, and others. Rise in hygiene concerns in the healthcare industry is expected to create significant opportunities for the hand sanitizer dispensing machine market.

Table 2. The need analysis of products during pandemic period

Sl. No. Requirement Products Users/market Scope for market and Innovation

1 Effective and safe treatment of Covid patients

Ventilators, Intubation box, Nebulizers

Critical Covid 19 patients

Modification of ambu into low cost ventilators

2 Safety of doctors and other medical assistants and staff

PPE, Santizers Doctors, Nurses, Assistants, Frontline service providers to covid patients

Scaling up of existing product

3 Safety of visitors, frontline workers and service providers to medical team

PPE, sanitizers, touch less devices such as Sanitizer, Soap dispensers

Frontline workers and Service providers

Scaling up of existing products and innovation of new products

4 Safety of public population

Mask, gloves, Sanitizers and touch less devices

Public population Scaling up of existing products and Innovation of new products

3.2 Mission Statement The primary objective of design is to keep the design simple. As a designer of the devices during pandemic

period to encounter the challenges of social life, there is little ambiguity into what the product does when it puts the words “safe, simple and affordable” up front in its mission statement. It is believed that “the foot operated sanitizer dispenser is a simple solution to the problems of social safety during Covid 19.

Table 3 illustrates the mission statement of the foot operated sanitizer dispenser. It is a pre-design activity which defines the product. The product is a foot operated sanitizer dispenser with bottle filled with liquid sanitizer. It should be compact and affordable. While there are some limitations like amount of sanitizer, cost, etc., it is important to decide other extra features required to enhance its utility.

Table 3. Mission statement of the foot operated sanitizer dispenser

Mission statement A device that presses the plunger of bottle is simple in operation with minimum parts is reliable in operation

Product description A foot operated sanitizer to disperse liquid sanitizer

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Project Goals Simple mechanism with reliable in operation with less number of components

Primary market The places where there is a chance for visit of public Secondary market Private offices and individuals Expected Characteristics Operation using foot

Bottle mounting location to the reach of hands Minimum efforts to be applied by foot

Stake holders Manufacturer, user and retailers Avenues for creative design

Add the value for minimum material usage

Project scope limitations The capacity of bottle Number of features incorporated Cost

3.3 Function structure

For sanitizer liquid to reach hands from the dispenser unit different activities are to be carried out and their relations are given by function structure. Fig. 2a shows function structure of the product. In function structure, thick line shows material flow and normal line indicates energy flow while information flow is shown by dotted line. It can be noticed from the function structure (Fig. 2a) that extreme right side can be grouped into a chunk based on the clustering process. This will become a modular design as shown in fig. 2(b). Next step for this design needs different concepts to be generated and evaluated for final design.

Fig. 2: (a) Function structure of the Foot operated Sanitizer (b) Modular design Architecture of the Unit

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3.4. Concept generation and evaluation Concept generation is the most critical step in the engineering design process [9]. A concept is defined as

both an “approximate description of the technology, working principles, and form of the product” as well as a “concise description of how the product will meet customer requirement” [10]. Concept generation is a procedure that begins with a set of customer needs and target specifications and results in an array of product concept design alternatives from which a final design will be selected. Concept generation requires a more abstract style of thinking than perhaps most engineers are used to [11]. The concept generation and evaluation of a foot operated sanitizer dispenser is discussed briefly as a case study in this paper. Figure 3(a) shows vertical plunger type sanitizer dispenser can. Conventionally the plunger needs to be pressed using fingers to disperse sanitizer. The idea of the design is that the plunger ( Fig. 3b) needs to be pressed finger touch less. So that it avoids the users to get exposure of virus in fingers as well as both the hands of users can be sanitized. Users can use their foot (Fig. 3c) to actuate while hands receive sanitizing liquid. A suitable mechanism can be used to connect the plunger movement and pedal in the reach of foot.

Fig. 3: (a) Manual press sanitizer dispenser, (b) Touch less sanitizer dispenser, (c) Foot operation

The critical operation and various options for dispensing sanitizing liquid from container are given in Table 4 as graphical representation, known as “morphology”. The operation of the device is decomposed into three critical functions. It is performed to find existing concepts relating to both the overall function and to the sub-function identified during the problem clarification step. The ideas for each function are provided as options.

For pedal actuation, in option 1, pedal is attached to wire rope with a hinge at rear side. In option 2, the pedal is directly fitted with a rod to move in vertical direction. In option 3, pedal is attached to a push rod with hinge at middle. The push moves up when pedal is pressed. For Pressing of plunger, in option 1, Pressing arm can make downward movement and return upward movement is by spring force. In option 2, a rigid arm as stopper is at the top of plunger and sanitizer bottle with holding unit moves up against gravity to get pressing of plunger. In this option, return of container is under gravity. Lifting effort varies based on liquid sanitizer level. In option 3, a cam rotates on the top of plunger which is fitted with body.

For connection pedal and pressing arm, in option 1, a wire rope is connected with pedal and pressing arm. In option 2, a rod is with thread at both ends to assemble pressing arm and pedal. In this, there are two guide bushes which are bonded with body to guide the movement of rod. In option 3, a wire rope is connected to the cam for rotation and other end to pedal. There are 3 options for 3 functions. Hence there are possibilities for 9 combinations to provide 9 solutions for complete functions of foot operated sanitizer dispenser. Average scoring is given after evaluation of each option in critical functions through information-gathering process. The implemented solution is cheaper and reliable when compared with other solutions in each option. The scores are evaluated by design team in brainstorming sessions. The total scoring for 9 solutions are arranged in descending order. The solution with highest score is selected. Option 2 is chosen for function A, option 2 for

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function B and option 2 for function C and the overall score for chosen functions of the device is 83%. This concept is taken forward for final design.

Table 4. Various options availability for mechanism of foot operated sanitizer

Functions Options

1 2 3

Pedal

actuation

(A)

Pressing of

plunger

(B)

Mechanism

to connect

pressing

arm and

pedal

(C)

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4. Design and analysis

The design of the device is finalized based on optimum functional score. The materials for each part in the design are selected to meet the functional requirement with adequate strength and manufacturability [12]. Analytical tool is used to verify the design of each part and the numerical simulation is done for the critical parts in the device.

4.1 Various components design Table 5 shows the bill of materials and functions of each part in the device. All the plastic parts are made

using ABS plastic material which is thermo plastic, recyclable and injection mouldable. ABS has sufficient tensile and flexural strength of 40MPa and 70MPa respectively to withstand the stresses induced during operation as well as continuous cyclic loading.

Table 5. The parts, function, materials and manufacturing process details of the device

Part No. Name Function Material Manufacturing process

1 Body Holding bottle holder, Wall mounting, enclosure for mechanism

UPVC Bought out and machining processes cutting and milling

2 Pressing arm Actuate the plunger ABS Injection moulding 3 Pedal assembly Foot operation ABS Injection moulding of

arm and pedal and bonding of both

4 Rod Connecting arm and pedal Mild steel Purchased as bright bar, Cutting and Turning

5 Springs Retracting arm after actuation

Spring steel Bought out

6 Guide bush Guiding push rod ABS Injection moulding and bonded inside UPVC tube

7 Bottle holder assembly

Holding bottle and bottle height adjustment during refilling bottle

ABS Injection moulding of 3 parts and assembled using bonding agent

8 M6 nuts Assembly of arm and pedal Mild steel Bought out

4.2 Numerical Simulation of Parts The modeling and simulation of parts are done by using SOLIDWORKS 2020. Figure 4 shows the results for

stress analysis of the arm. Plunger reaction force is applied at the point of contact of plunger and internal surface which is mounted with connection rod is constrained. The maximum stress induced at the top surface of the arm is 1.8MPa as shown in Figure 4 which is very less when compared to the strength 40MPa of ABS plastics. Figure 5 shows the results for stress analysis of the pedal assembly. To simplify the simulation, the pedal plate and bottom arm are considered as single entity. Foot force is applied as uniformly distributed load at the area of contact of pedal plate and internal surface which is mounted with connection rod is constrained. The maximum stress induced at the top surface of the arm is 5.4MPa in a very small region as shown in Figure 5 which is very less when compared to the strength of ABS plastics with high margin safety factor.

Similarly, the stress analysis of the mild steel connecting rod has also been carried out. The rod is subjected to tensile force of 50N and a bending moment 3 Nm due to plunger reaction and pedal force. Friction force between guide bushes is neglected. The maximum stress induced is 39 MPa which is very less when compared to the yield strength of the mild steel.

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5. Rapid Prototyping and Product Development

Prototypes are not only the physical embodiments of a product almost at the end of the development process. The need and the resulting short time to launch of the device require the quick availability of models and samples during the whole development process [13-14]. Besides the conventional manufacturing of physical prototypes example CNC-machining, the 3D printing technologies gain more importance. 3D printing provides the possibility to produce a physical artefact directly from its CAD model without any tools. Hereby, it is possible to build the prototype of a complex part already within a few days. With conventional prototyping, it would take several weeks to build the same part. With the aid of 3D printing, it can be examined how far

Fig. 4: Stress analysis of Plunger activation lever

Fig. 5: Stress analysis of Foot pedal

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requirements are met. Further, they help to learn rapidly, to minimize mistakes and to integrate different functions [15].

Figure 6 shows the RPD process that is followed to develop foot operated sanitizer/soap dispenser. CAD and 3D printing technologies are used for rapid prototyping and CNC machines are used for rapid tooling development to make parts in plastic injection moulding process. CNC machines are used for some parts of the product

Fig. 6: Rapid Product Development process followed in Foot operated sanitizer/soap dispenser

Prototypes are not only the physical embodiments of a product almost at the end of the development

process. The need and the resulting short time to launch of the device require the quick availability of models and samples during the whole development process [13-14]. Besides the conventional manufacturing of physical prototypes example CNC-machining, the 3D printing technologies gain more importance. 3D printing provides the possibility to produce a physical artefact directly from its CAD model without any tools. Hereby, it is possible to build the prototype of a complex part already within a few days. With conventional prototyping, it would take several weeks to build the same part. With the aid of 3D printing, it can be examined how far requirements are met. Further, they help to learn rapidly, to minimize mistakes and to integrate different functions [15].

Figure 6 shows the RPD process that is followed to develop foot operated sanitizer/soap dispenser. CAD and 3D printing technologies are used for rapid prototyping and CNC machines are used for rapid tooling development to make parts in plastic injection moulding process. CNC machines are used for some parts of the product.

Rapid Product Development Process

Using digital technology for design and prototyping Design Tools: CAD software

Prototyping: 3D printer, CNC machining

Validation and testing of prototype

Feedback and implementation of design changes

Rapid Manufacturing Planning

Rapid building of tools

Design Tools: CAD and CAM software

Rapid Tools: CNC Machines Building of parts by injection moulding and CNC

machining of parts Injection moulding of plastic parts, CNC

machining and assembly

Testing and validation of product Fatigue and Reliability tests

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5.1 Design and manufacturing of Moulds The ABS parts are made using a semi automatic injection moulding machine. The mould plates are designed

to fit the clamping area of the injection moulding machine. Mild steel is used as materials for mould and the mould cavity is machined using 3 axis CNC machine. Figure 7 shows the two parts mould for knob embedded with M6 screw. The screw is kept in the mould prior to injection of molten ABS plastic. Dowel pins are used to match the two plates of the mould.

Fig. 7: Mould used for injection moulding of plastic knobs

5.2 Correction and redesign of moulds Figure 8 shows the two parts of a mould used to make pipe slide which is bonded with tray of bottle holder.

In the first version of mould design, the part was made with hexagonal configuration to clamp UPVC pipe. There was not enough clamping forces generated to provide sufficient strength to prevent sliding over the pipe. Also there was a challenge in releasing of part from mould during injection moulding. Then the part was redesigned with circular cross section and to provide adequate clamping force and easy retrieval from mould after solidification of part in injection moulding.

Fig. 8: Mould used for injection moulding of pipe slide

5.3 Injection moulding of parts Figure 9 shows the ABS plastic parts that are manufactured by injection mould for making one foot operated

sanitizer dispenser. The parts are made using ABS granules of red and blue colours to provide two variant in

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product appearance. The parts are made in 50 or 100 numbers in batches to assemble the devices in a batch of 50 or 100 numbers respectively. The heater temperature set in injection moulding machine is 240° C and sufficient clamping pressure is set in hydraulic power pack of the injection moulding machine. Mould release agent is applied on mould cavity prior to each injection. The releasing of product from mould is done after curing and ejected the parts without damage. Improvisation in mould is based on initial trials for smooth sequence of operation of injection moulding. Removal of runner and unwanted projections are done after making each batch of parts.

Fig. 9: Plastic parts of the Foot operated Sanitizer dispenser

5.4 Assembly of the device The assemblies of parts are designed to ensure free from malfunctioning. The Unplasticized Polyvinyl

Chloride(UPVC) body tube is machined with slots in same orientation to align pressing arm and pedal arm in same line. Sub assemblies of injection moulded parts are shown in Figures 10 and 11. Part 1(Arm) and part 2(Pedal plate) are bonded using bonding medium of brand Anabond model 555M having lap shear strength 2MPa. Figure 11 shows the assembly of bottle holder having four parts pipe slide, tray, ‘c’ cover and knob. Pipe slide, tray and ‘c’ cover are bonded in respective bonding area and knob is screwed in pipe slide. Wall clamp and sliding bushes are bonded with UPVC pipe externally and internally respectively. Figure 12 shows an assembled device with all the parts. The device is fixed with wall using four screws through plastic plugs. Also the device is light weight and can be mounted in wooden or metallic stands to use as portable units.

Fig. 10: Assembly of pedal with bottom lever

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Fig. 11: Assembly of sanitizer container holder

Fig. 12: Foot Operated sanitizer and Soap dispenser

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6. Testing and Failure Analysis

The parts of foot operated sanitizer dispenser are made using steel, Unplasticized Polyvinyl Chloride(UPVC) and Acrylonitrile butadiene styrene(ABS) plastic. The properties of these materials are considered based on manufacturers’ data sheet during the design and simulation processes. Some of the parts are bonded to get the component of the device. The components are tested experimentally to find bonding stress and are verified with the bonding strength prescribed by the bonding medium manufacturer. Each part is visually tested for any defect or excess material. Inspection check list is made to check the device for correct assembly and manual force applied in various parts. After assembly, the device is functionally tested for correct operation. The fatigue test is done for 105 cycles on the device to find fatigue life of the device. The Sanitizer unit sustained these cycles without any damages. Figure 13 shows the device tested in a pneumatically operated fatigue testing set-up. Pressure sequence valve ensures that the maximum pressure of 4 bars is applied to pedal at the end of pressing stroke and it is equal to load of 20 kg which is about 4 times of normal load applied during operation. A limit switch is used to confirm completion of each stroke of pneumatic actuator and the limit switch signal is considered to send signal to counter.

Fig. 13: Fatigue cyclic loading set-up

The critical functional parts such as pressing arm, pedal assembly and connecting rod are simulated to find the deformation and stress. It is found from analysis that the stresses induced in the critical functional parts are well within their elastic limits having factor of safety more than 5. The major failure mode of critical

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functional parts, pressing arm and pedal assembly is due to bending. The connecting rod is subjected to failure modes due to tensile load and bending. The tensile stress induced in connecting rod is very marginal for plunger pressing force. The bending stress near pressing arm mounting at top end and near pedal assembly at bottom end of connecting is also a failure mode. Even the sufficient margin of safety factor is considered, the failure due to fatigue needs to be verified. That is the reason for accelerated fatigue load testing of the device.

Failure of bonding is also another important failure mode. The debonding of plastic parts in non critical parts becomes critical failure mode. The device is used in common places as well as soap dispensers in toilets; there is possibility for exposure of various chemical agents such as commercial grade Harpic, Bleaching powder etc. The bonding medium to assembly plastic part is chosen to resist these chemicals as well moisture. Partial loosening of wall mounting screw create cyclic forces to bonding medium between UPVC pipe and wall mounting brackets at top and bottom.

Malfunction of the device is expected due to improper clamping and positioning of sanitizer holder tray. For mitigate this, a label indicating direction of use is pasted on bottle holding tray. Improper wall mounting of the device is also another expected malfunction of the device. This is addressed by providing installation instructions to the stake holders.

7. Value Analysis

Value Analysis is one of the major techniques of cost reduction and control. It is a disciplined approach which ensures the necessary functions for the minimum cost without diminishing quality, reliability, performance and appearance.

It eliminates the unnecessary costs which add neither to quality nor to the appearance of the product. It is a systematic application of techniques to identify the functions of a product or a component and to provide the desired function at the lowest total cost.

Table 6 shows the cost of each part including raw material and tooling for first 500 units manufacturing. Table 7 shows the value analysis of the device. The weight factors and scoring are assigned to each part based on features and functional requirements of the part. The target cost of the mechanism is Rs. 200 and actual cost based on table 6 is Rs. 243. The actual cost of few parts is less than target cost and the actual cost of many parts is higher than target cost as expected. This analysis shows the scope for improvement. In this example the body, container holder and guide bush are costing more than the targeted values. Thus in the next version these components can be optimized for less cost.

Table 6. Cost and material details of Sanitizer dispensing unit

Part No.

Part Name Material Weight (g)

Cost of raw material and manufacturing (Rs)

Tooling cost per unit for first 500 units (Rs.)

Total cost(Rs.)

1 Body UPVC 360 50 - 50

2 Pressing arm ABS 15 5 20 25

3 Pedal assembly

ABS 25 10 20 30

4 Rod + nuts Mild steel 350 20 - 22 5 Springs Spring steel 5 15 - 15 6 Guide bush ABS 10 5 20 25

7 Bottle holder assembly

ABS 90 16 60 76

Total weight = 865 grams Total cost 243

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Table 7. Value analysis for foot operated sanitizer

Customer

requirements/

Functions

Imp

ort

an

ce

Mechanisms

Δ Strong correlation weight factor = 5; ○ Moderate correlation weight factor = 3;

ʘ Weak correlation weight factor = 1

Pe

da

l

Co

nta

ine

r h

old

er

He

igh

t a

dju

stin

g

un

it

Bo

dy

Pre

ss a

rm

Sp

rin

g +

Ro

d

Gu

ide

bu

sh

Easy foot

operation

25 ○

75

○

75

Δ

125

○

75

Stability of

sanitizer unit

30 Δ

150

○

90

Δ

150

○

90

Ease of fixing and

maintaining

20 Δ

100

Δ

100

○

60

Durability of the

unit

15 Δ

75

Δ

75

○

45

Δ

75

○

45

Appearance 10 ʘ

10

○

30

Δ

50

ʘ

10

Column weight 1505 160 280 265 260 220 200 120

Mechanism weight 1.0 0.106 0.186 0.176 0.173 0.146 0.133 0.080

Mechanism target

cost(Rs.) 200 21.2 37.2 35.2 34.6 29.2 26.6 16

Mechanism actual

cost(Rs.) 243 30 50 26 50 25 37 25

8. Summary

Design of a foot operated sanitizer dispensing unit has been accomplished using well-known product design principles which enhance designer’s intuition. This work discusses the various stages of design, selection of material for cost effective design, arriving manufacturing processes based on availability of limited resources in an academic Institution. Function structure is developed which resulted into a modular design of this unit. The 3D printing of prototype, testing and validation of the foot operated sanitizer dispenser have also been carried in this study. Each part in the product is modeled and analysed using a software tool to find the stresses and deformations. Ergonomics, Value analysis, failure analysis, and accelerated fatigue test contributed to the complete design of this product. The dispensing unit developed in this study is able to actuate vertical plunger type 500 ml sanitizer/liquid soap dispensers. This unit weighs only 865 grams and can be mounted in wooden or metallic stands to use as portable units.

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Acknowledgement

The authors of the paper acknowledge the support of the management of IIT Madras for providing support to access the research and manufacturing facilities of Institute during pandemic period and lock down. The authors are highly appreciating the staff of members Mr. Chandranath, Mr. Arun, Mr. Damodaran, Mr. P. J. Winston, Mr. Sudheer and Mr. Danasekaran of Central Workshop for their direct support and other staff members who supported indirectly to this study.

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