Custom Plastic Injection Molding Terms You Need To Know

1. 20 Common and Uncommon Plastic Injection Molding Terms Greenleaf.biz | (865) 988-5661 310 Bussell Ferry Road, Lenoir City, TN 37771

2. 20 Common and Uncommon Plastic Injection Molding Terms Learn the Plastic Injection Molding “lingo” to better communicate with engineers, project managers and mold technicians. It is our pleasure to produce the annual guide to over 200 injection molding industry terms. Download the entire ebook here. To be fair, that’s a lot of words, so we asked our mold techs to select 10 of the most common. Combine the slightly more obscure terms to the list of common ones, and you’re ready for a factory tour and maybe even a project design discussion! 1

3. 10 Injection Molding Terms Mold Techs Use Daily BURN – When the air temperature inside the mold exceeds the flash point of the plastic, a “burn mark” is made. If something is “burned” in molding, it shows evidence of thermal decomposition through some discoloration, distortion and localized destruction of the surface of the plastic. EJECTOR CONFIRMATION SWITCH – A switch used to prevent mold damage by detecting if the ejector plate does not fully return to home position. FLASH – Extra plastic attached to a molded part along the parting line or other shut-off locations in the mold. 2

4. 10 Injection Molding Terms Mold Techs Use Daily GUIDE PINS – Devices that maintain proper alignment of the core and cavity while the mold closes. These are also called “leader pins.” JETTING – A turbulent flow of resin from an undersized gate, or thin section, into a thicker mold section. This is opposed to a laminar flow of material progressing radially from a gate to the extremities of the cavity. KNIT LINE – A mark on a molded piece made by the meeting of two flow fronts during molding. It can also be called a “weld line.” 3

5. 10 Injection Molding Terms Mold Techs Use Daily NOZZLE TIP (REMOVABLE) – A replaceable tip that installs into the end of the molding machine’s nozzle. Nozzle tips must be matched to the mold surface (for sealing off high injection pressures), and to the orifice of the mold sprue. PLASTICIZE – To soften a material and make it plastic or moldable either by means of a plasticizer or the application of heat. PURGING – Cleaning one color or type of material from the cylinder of an injection molding machine by forcing it out with a “purge compound,” or with the new color/material to be used in subsequent production. SHORT SHOT – A molded part produced when the mold has not been filled completely. 4

6. 10 Obscure Injection Molding Terms You Should Know AGING – Refers to the change of a material with time under defined environmental conditions, leading to either improvement, or the deterioration of certain properties. CAST – To form a “plastic” object by pouring a fluid monomer-polymer solution into an open mold where it finishes polymerizing. CONDUCTIVE PLASTICS – Materials that allow a current or charge to travel through it. Conductive plastics are hybrid polymers that are electrically conductive or static dissipative. These plastics are engineered, using additives such as copper, silver, aluminum, carbon black and carbon fibers, to have conductivity characteristics. 5

7. 10 Obscure Injection Molding Terms You Should Know CURE – To change the physical properties of a material by chemical reaction to make it more stable & functional. The process may include condensation, polymerization, or vulcanization. ELASTICITY – The property of a material by virtue of which it tends to “recover” to its original size and shape… after deformation. FLAME RATING – An internationally accepted plastics “flammability” testing standard created by Underwriters Laboratories. INSERT – An integral part of a plastic molding consisting of metal, or other material, which may be molded into position or may be pressed into the molding after the molding is completed. 6

8. 10 Obscure Injection Molding Terms You Should Know LIM (LIQUID INJECTION MOLDING) – A process used to produce silicone parts using an injection molding machine. The silicone is a thermoset resin, and is injected as a two-part liquid into a heated mold where the silicone rubber is solidified (vulcanized). NOTCH SENSITIVITY – The extent to which the sensitivity of a material to fracture is increased by the presence of a surface in homogeneity such as a notch, a sudden change in section, a crack, or a scratch. Low notch sensitivity is usually associated with ductile materials, and high notch sensitivity with brittle materials. PERMANENT SET – The increase in length, expressed in a % of the original length, by which an elastic material fails to return to original length… after being stressed for a standard period of time. 7

9. About GreenLeaf Industries GreenLeaf Industries is an ISO 9001 registered manufacturer that consistently adheres to all its standards to provide our clients with consistent, reliable, quality automotive and industrial plastic parts. We are an American injection molding company, unafraid to compete in the world market and determined to succeed. Established in 1999, we take pride in our high-quality craftsmanship and superior customer service. 8

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