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PITFALLS IN INJECTION MOULDING OF PLASTICS
During my tenor as Regional Manager of WINDSOR in Madras between 1978 and 1990, I had come across numerous problems of machines, moulds, materials, processing, support equipment. Each of these affected my customers' performance and also profitability. I took up their problems seriously and tried to apply my mind to understand the root causes of these problems. I used to discover and learn new things every time I tried to solve the problems. I used to document these learning and later on I tried to fit all jigsaw pieces to form a whole picture. The end result is this book " A Guide to Injection Moulding of Plastics". Truly I should be grateful to my customers who gave me this opportunity to understand the subject. Now I want to distribute this knowledge to all - particularly to the students' community.
Steps in Injection Moulding
Injection Moulding of plastics involves quite a few steps before actual moulding operation.
The first step has to be
In mechanical engineering Part design has to be manufacturable. Similarly plastic part has to be mouldable to high degree. If moldability is poor than, you have all types of quality and production problems. Therefore part design has to be modified to make it more than 90% mouldable. General assumption that any geometry of the part is mouldable perfectly is not correct. General understanding- that once the mould is filled with the melt every thing has to be perfect- is not correct.
BASICS of Physics and engineering
Trainability of the people depend on their mindset and their understanding of basics of school physics. Those who can recall meaning or definition of each technical terms -he uses every day- is trainable. To see BASIC TECHNICAL TERMS - Physics, click here.
It is necessary to understand HEAT, TEMPERATURE. THERMAL CONDUCTIVITY and HEAT TRANSFER. In fact, with out understanding heat exchange that is taking place in the mould one can not understand the causes for inconsistent- shot to shot variation of - dimension, dimensional distortion or warping.
Other important basic technical terms related to process are Viscosity, Shear, Pressure/stress, Speed, Power, Energy. All these terms are learnt in secondary school. Therefore, knowledge of school physics is adequate to understand the processing of plastics. To see BASIC TECHNICAL TERMS - Polymer Process, click here.
Let us see the Engineering Basics in Injection Moulding Machine.
Let us understand that the learning of any subject. The subject can be broken-down to number of elements / parts. These elements/parts can be grouped in to two groups. This grouping has to be based on the ease of grasping the each parts/elements.
Things to KNOW
What is required to know about Injection Moulding of Plastics?
Click here to know about Injection Moulding Process.
BASICS of Polymer
Click here to know about Basics of Polymer, Properties and Application.
What is required to know about Plastics material, Mould and Machine?
INJECTION MOULDING PROCESS
Injection Moulding Process involves
Plasticating refers to conversion of plastic granuals to flow-able melt. It happens inside the screw barrel assembly of the injection unit in the Injection Moulding Machine.
Moulding refers to shaping of plastic melt inside the mould.
Understanding PITFALLS of Quality problems.
The root causes of quality problem may or may not lie in the present step. The mistakes of the earlier steps may not be possible to correct at the later steps. Some time
it may be possible to correct partly. Such corrections are expensive. The problems originating from the present step can only be solved in the present step.
THREE BALANCING TRICKS
I can summarize the successful and consistent moulding to three balancing tricks;
Any unbalancing on the above three balances will result in moulded-in stress. This is the biggest culprit for over 50% part failure
PITFALLS- not Obvious
My book " A Guide to Injection Moulding of Plastics" discusses the following not obvious topics;
if you are concerned with plastics molding,
Order your copy NOW.
"Keywords" -"plastics, polymer, injection, molding, machine, part design, mold design, mould, CAE, CAD, CAM, Moldflow, quality, molded-in stress "
|Author: Prabodh C. Bolur||..||PLASTINDIA-2000 Photos||MoldFlow Users Meet||Seminar on FRP||IPI's Lecture Meeting at Mumbai|
||IPI-AITEC Seminar||Training At Nilkamal Plastics||Windsor Functions-old||Answers to YOUR questions||...|
|HOME||Contact-to buy this book||Things to know- Process||Things to know- Polymers||Things to know- Part Design||Things to know- Mould|
|Things to know- Machine||Injection Moulding Process||Screw Plasticating||Moulding||Key factors influencing proces||Shear strain curve|
||Thermal stability||Balancing melt Flow||Balancing Heat||Freezing||Quality Problems|
||Moulded-in Stress||Shrinkage||Inconsistent Dimension||Sink-mark||Weld-lines|
||CYCLE TIME||Plastics Part Design||Flow Analysis||..||..|
|Engineering Basics in Machine||Glossary of technical terms- Physics||Glossary of technical terms- Polymer process||Myth||Understanding Mould Cooling Channels||Ideal Moulding Shop|
||Typical Barrel temp.||Barrier Screw||Energy Efficiency||Failure Analysis||Metering Stroke|
||Plastics Part Design||Polymers Applications||Polymers Applications||Polymer Basics||Properties of Polymers|
|Properties of Polymers||Process Guide||Process Limitation||Quality in Moulded Parts||Residence Time||Speed Setting in IMM|
|Tolerance in molded parts