Setting Conditions, Producing, and SamplingTHEORETICAL BACKGROUND

The machine setting at the beginning of each injection molding processprocedure should be as close as possible to the most desirable processingconditions. To start with a calculated guess of the possible process conditionfor a given material, we should also consider some important factors like:injection molding machine size, material grades, mold design, etc. Processconditions settings is influenced by these following parameters: Injection molding machine Injection mold Material Geometrical parameters of the part Desired properties of the productData inputs are based on each stage of the machine work cycle as shownbelow:(

Produce Good Sample Product

Prepare all materials & equipment for running the machine, e.g., spanner,screw driver, etc. Use previous Mold Setup Chart & QA product approval, if any, to runthe machine. Try to get best machine setting for the product & take 3-5 good samplesfor QA visual & functional check/ testVisual Appearance Checking One product performance criterion is to check product condition visually.

_ Be sure that the product is inspected at its front, side & back._ If defects are noticed, please do the necessary adjustments until you get a good product

Functionality Checking (Product Specifications)

One product performance criterion is to measure good functioning ofproduct using some tools & methods

_ Ensure the scale is reset to zero_ Place one full shot on the scale_ Compare the weight to the standard shot weight_ Product Dimension_ Warpage or flatness_ Flash, shorts or sink

Machine Setting Conditions and Trial Run

1. Go to the molding machine area.2. Familiarize yourself with the display of the control panel. Copy theparameter setting currently in the display panel to your worksheet for thefollowing: Mold Closing Mold Opening Barrel Temperature Dosage Holding3. Observe and try to familiarize yourself with the entire injection moldingprocess cycle.4. Run the machine based on the current settings and collect samples.PART II Sampling1. Take 5 samples of the product.2. Check each of the products using Visual Checking and FunctionalityChecking method.3. Record the results using the forms found in your worksheet.

Machine Setting Conditions and Trial RunSETTINGS FOR MOLD CLOSINGSETTINGS FOR MOLD OPENINGSETTINGS FOR BARREL TEMPERATURESETTINGS FOR DOSAGESETTINGS FOR INJECTIONSETTINGS FOR HOLDING

THEORETICAL BACKGROUND

INJECTION SPEEDInjection speed is the filling speed of the molten material in to the mold withthe forward movement of a screw. Unit: cubic centimeter (cc)/sec.

INJECTION PRESSURE (Pmax)Injection pressure is the term for the pressure applied to the molten materialwhen a screw moves forward to inject it from the nozzle at high speed. (unit:Bar )

HOLDING PRESSUREThe pressure applied to the molten material after completion of InjectionPhase. It pushes further plastic melt into the cavity before gate freezing.Unit: Bar.

SHOT CAPACITYThe maximum amount of plastic melt that can be injected from the barrel ofan injection molding machine in a single shot. Unit: grams of polystyrene.

INJECTION RATEThe injection rate is expressed in terms of the volume of the molten materialwhich can be injected in the unit time. Unit: cm3/s.

SCREW SPEEDThe rotational speed of the screw during dosing. It is expressed in rpm(rotations per minute).

BACK PRESSUREThe molten material is plasticated and kneaded by the rotation of a screw andtransferred to the tip of the screw, where the molten material accumulatesand recoils, causing the backward motion of a screw. In order to suppressthis movement, slight pressure is applied to the injection cylinder side. Thisis called back pressure. Unit: bar.

CLAMPING FORCEClamping force (CF) is the force which keeps the mould closed duringinjection.Required Mould Clamping ForceClamping force ( F ) in the diagram should bebigger than the force ( f ) which makes themould open during injection