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First color material: PA66+20%PTFE
Second color material: PA+60%GF
Above two materials have similar properties and good adhesion.
PA66+20%PTFE Basic features: self-lubricating, super wear-resistant
Polytetrafluoroethylene (abbreviated as PTFE), commonly known as "Plastic King".
White waxy, translucent, excellent heat and cold resistance, can be used for a long time at -180 ~ 260℃.
This material has characteristics of acid, alkali resistance and resistance to various organic solvents, and is almost insoluble in all solvents.
At the same time, PTFE has characteristics of high temperature resistance, and its friction coefficient is extremely low, so it can be used for lubrication, and it has also become an ideal coating for easy cleaning of inner layer of water pipes.
Polyamide 66 or Nylon 66 (abbreviated as PA66):
Continuous heat resistance of 80-120℃, equilibrium water absorption rate of 2.5%, so dimensional stability is poor.
It is resistant to corrosion by acids, alkalis, most inorganic salt solutions, halogenated alkanes, hydrocarbons, esters, ketones, etc., but is easy to be soluble in polar solvents such as phenol and formic acid. It has excellent wear resistance, self-lubrication and high mechanical strength.
Basic characteristics of PA+60%GF: self-lubricating, high strength.
PA has good fluidity during molding, but molding shrinkage rate is large, resulting in poor product dimensional stability;
Melting point of glass fiber is 680℃, boiling point is 1000℃, and density is 2.4～2.7g/cm3.
Softening temperature can reach 550~750℃.
Glass fiber has good heat resistance and is a high-grade insulating material with good insulation, which is suitable for production of thermal insulation and fireproof materials.
Combined with characteristics of glass fiber, injection molding alone is impossible.

 

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Orange part of second color is all on the side of master mold, which ensures consistency of rear mold.

 

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Parting line of the first color, 1/3 is on the side of master mold, to prevent sticking to front mold, and it is allowed to have glue positions on the front and rear molds. Key is to prevent risk of product sticking to front mold. When sealing second color of back mold side, try to seal it as flat as possible.

 

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The first color adopts needle valve type hot runner to feed glue.

 

Since product requires mold cavity to be: 8+8
Soft rubber products are glued at the edge, and hot runner space is not enough, so hot runner is transferred to cold runner for dispensing.

 

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Primary and secondary color feed styles

 

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Product adopts a round thimble ejection style.

 

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The overall structure of mold.

 

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Position of injection nozzle of the first color and second color injection molding machine.

 

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The overall style of back mold, the first color on back mold side is exactly same as second color. After the first color is injected, product remains on back mold side. When turntable on injection molding machine rotates 180 degrees, after second color is produced, product is ejected.

 

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Second color dispensing glue adopts button machine structure to complete demoulding of dispensing nozzle, and realizes fully automatic production.

 

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Steps for opening two-color mold are as follows:
The first step is to open mold, and open mold at point where cold runner enters glue to ensure that dispensing port is separated from product.
Second step is to open mold. Cold runner is separated from hot runner through pulling force of tie rod, so that cold runner can be automatically separated, or cold runner can be taken out by a robot.
Third step is to open mold, and front and rear mold plates are opened normally.
Fourth step is to open mold. Ejector stick on injection molding machine pushes ejector plate to eject product smoothly.
Step 5: Turntable of injection molding machine rotates 180°
Step 6: Clamp injection molding machine
Step 7: carry out next repeated action, which is called a mold forming cycle.

 

 

 

 

Main points of this set of mold design:
1. As long as GF material is added, front and rear mold cores need to be heat-treated materials (S136).
2. In the case that rear mold needs to be exactly same, machining accuracy and life are required to be higher than front mold core, so heat treatment hardness of front mold core is HRC48~52°, and heat treatment hardness of rear mold core HRC58~60°.