10 things to pay attention to in mold parting process of plastic molds

Time：2022-10-13 08:37:00 / Popularity： / Source：

Note 1 during parting process: shrinkage rate

Shrinkage rate of product determines dimensional accuracy control of molded product. If shrinkage rate is not accurate, the entire front and rear mold cores will be scrapped.
For conventional materials, use conventional shrinkage rate. If it is a modified material, you need to know material property table, and confirm shrinkage rate according to physical property table.
If shrinkage rate is not sure, first do glue reduction treatment, and do iron retention treatment on mold.

Note 2 during parting process: parting surface

Choose planes first, then bevels, and then arcs, curved surfaces, 3D surfaces, and so on.

Note 3 during parting process: insert against broken surface

It is preferred to use a flat surface against a broken surface,
When inserting broken surface, it is first to use large plane to insert broken surface to seal glue.

Note 4 during parting process: there is an R angle optimization at the root of parting surface

If there is an R angle under parting surface, R angle needs to be treated by stealing glue 0.03~0.05mm

Note 5 in parting process: optimization of parting surface level difference

Under normal circumstances, A side and B side are appearance surfaces, try not to produce a frontal step difference,
In the case of a step difference, basically do 0.03~0.05mm steal glue on male mold side.
When there is a large surface on parting surface, it is necessary to make a step difference, small surface is given priority to be steal surface, and try not to have a positive step difference on large surface.

Precautions 6 in parting process: glue feeding point

Different styles of glue feeding points need to be processed by stealing glue in product, so as not to affect appearance and assembly.

Precautions 7 during parting process: prevent product surface from shrinking

During parting process, if it is found that thickness of product is uneven, it is necessary to do glue stealing treatment to prevent surface of product from shrinking.

Note 8 during parting process: BOOS column of product needs to be a crater to prevent surface from shrinking.

Height of crater is basically controlled at 0.5~0.8mm, which needs to be determined according to average meat thickness of product. Under normal circumstances, same part of needle in BOOS column should also be treated with glue.
Reference Specification for Crater Design
If wall thickness of Boss column or bone position of product is greater than 0.5 times wall thickness of main body (0.4 times for mirror product), crater needs to be designed.
For design of crater at Boss column of product, please refer to Figure 1 below;
For design of crater at bone site of product, please refer to Figure 2 below ;

Product body thickness (mm) T	Crater size (mm)
Product body thickness (mm) T	H	W
3.0	0.5	0.2
2.5	0.5	0.2
2.2	0.4	0.2
2.0	0.3	0.2
1.8	0.3	0.2
1.5	0.2	0.2

Crater Design Application Examples
Design of shrinkage at boss column: As shown in figure, since wall thickness of product is 2.21mm, and boss wall thickness is 1.8mm greater than 0.5 times thickness, it is easy to shrink. According to above reference table and diagram, crater of following size can be used, so as to avoid shrinkage defects.

Anti-shrinkage design at bone position: As shown in figure, since thickness of main body of product is 2.3mm and thickness of bone position is 1.5mm, local thickness at intersection of two bone positions is too thick (greater than 0.5 times thickness of main body), which is prone to shrinkage. According to above reference table and diagram, crater of following dimensions can be made to avoid shrinkage defects.
parting surface

Note 9 during parting process: inserts

Principle of inserts: exhaust and processing, and achieve effect of foolproof.

Note 10 during parting process: exhaust

Under normal circumstances, exhaust should be done in front mold. If thickness of product is within 1.5MM, peripheral exhaust should be done as much as possible.

Gud Mould Industry Co., Ltd