Injection Mold Accreditation Standard

Time:2023-05-19 09:56:01 / Popularity: / Source:

Purpose: To establish a standard for mold approval from three aspects of mold structure, plastic parts quality and injection molding process requirements, to evaluate and score mold quality based on this, hoping to continuously improve mold quality; to ensure that molds can be put into production normally, and produce qualified plastic parts to meet requirements of product design.
Injection Mold 

1. Mold structure

(1) Mold material

1. Steel used for each plate of mold base is not less than 1050 steel. (equivalent to Japanese ace steel)
2. Surface hardness of material used for embryo, side nails, back nails, center support, and center support edge is not less than HRC60.
3. Front mold and front mold inserts made of beer ABS and HIPS are made of super P20 steel (such as 718, M238, etc.). General P20 steel (such as MUP, M202, etc.) is used for rear mold, and 1050-1055 steel or better steel is used for rear mold insert.
4. For PC, POM, PE and other corrosive materials, front and rear molds and their inserts need to use 420 steel (such as S136, M300, M310, etc.).
5. Steel used for mirror mold is 420 steel (such as S136, M300, M310, etc.).
6. Surface hardness of lifter and swing rod shall not be less than HRC35, and surface hardness of push plate shall not be less than HRC28.
7. If customer specifies that mold steel should be used, mold factory should meet customer's requirements.

(2) Mold should have a structure

1. Mold logo: outside of mold should be marked with words according to customer requirements. P/N number and grade of plastic parts are marked on position specified by customer in mold base. Cavity number should be marked on one mold with multiple cavities, and insert number should be marked on multiple inserts according to design requirements.
2. Mold should be installed with a suitable flange ring, and a standard size mold pit should be opened.
3. Three-plate mold should be equipped with buckle locks and locking nails, should be installed with pulling hooks and nozzle plates, and elastic rings should be opened first.
4. Bottom plate of mold should have a qualified ejector hole, and hole position should meet ejection balance requirements.
5. Mold thimble plate should be equipped with a return spring. When closing mold, front template should first touch return pin, otherwise mold should be equipped with a reset mechanism (there is a separate requirement for slide structure).
6. Slide structure.
² Slide movement should be smooth, contact surface should be provided with oil grooves.
² A spring that makes slide pop up should be installed on slide, and a limit device should be installed.
² Height of Huff blocks moving in height direction cannot exceed 2/5 of length of guide chute.
7. Ejection mechanism.
² Thimble should be set so that there is no permanent deformation, white top, and no effect on the appearance of plastic part when plastic part is demolded.
² Thimble mechanism should be flexible, reliable and free from wrong actions.
² When top surface of thimble and cylinder is not flat, thimble and cylinder should be positioned.
8. Garbage nails should be evenly arranged on floor, and height of garbage nails should be consistent.
9. Large mold of 4545 or above should be equipped with a middle bracket, number of cylinders in a set of molds reaches or exceeds 16, and a middle bracket should be added.
10. Diameter and length of runner should be processed reasonably, process should be shortened as much as possible under premise of ensuring forming quality, and cross-sectional area should be reduced to shorten filling and cooling time. At the same time, loss of plastic in gating system should be the least. Runner should generally be provided with a cold well.
11. Cavity distribution should be reasonable, and should conform to principle of simultaneous filling of each cavity. Gate setting should not affect appearance of plastic part, satisfy assembly of plastic part, and try to minimize residual amount of gate under conditions of production.
Injection Mold 
12. Cooling system.
² Surface of water delivery channel should make temperature difference of each part of mold surface within 10 ℃.
² Location of inlet and outlet holes of water delivery channel does not affect installation, and size of throat is 13mm.
² Inserts and slides on the surface of cavity should generally be connected to water, inserts such as battery pockets, handle positions, and horn positions must be connected to water.
² Mold water channel should be watertight, words "OUT" and "IN" should be marked at inlet and outlet of channel. If there are multiple groups of water transport channels, group number should also be added.
13. Battery pockets and other parts that exert a large tightening force on the front mold should evenly add hook needles to corresponding rear mold parts.
14. Mold structure ensures smooth exhaust.
15. If height of column exceeds 20mm, cylinder should be used. If height of column exceeds 25mm, glue should be added evenly according to design requirements.
16. Mold should evenly distribute braces according to strength requirements to prevent mold from deforming.
17. Stress center of mold cavity should be consistent with mold center as far as possible, and cavity center should not exceed 25% of mold center at most.
18. If surface of shape will cause shrinkage, a crater should be added to post of corresponding post mold.
19. Parting surface is a one-way slope and a large deep cavity mold, and parting surface should be equipped with a reliable self-locking device.

(3) Structure that mold does not allow

1. Mold is not allowed to have sharp steel and thin steel with a height greater than 2mm and a thickness less than 1mm.
2. Thimble is not allowed to contact front mold except BOSS column.
3. Abnormal noise is not allowed when mold is opened and closed.
4. Red lead test is not allowed within 5mm of edge of cavity, and red lead test of parting surface is not allowed to be less than 80%.
5. All fastening screws are not allowed to loosen.
6. All crochets are not allowed to appear in different directions.
7. Plastic parts are not allowed to have mold sticking phenomenon.
8. Mold is not allowed to have unbalanced ejection.
9. Front and rear mold plates in height direction of mold are not allowed to lack pull holes.
10. Missing or wrong parts are not allowed in mold assembly.

2. Quality of plastic parts

(1) Basic size

1. Geometric shape and dimensional accuracy of plastic parts should meet requirements of formal and effective mold opening drawings (or 3D files).
2. General structure size standard.
² Adhesive parts are generally required to have an average adhesive thickness, and non-average adhesive thickness should meet requirements of drawing.
² Stud root diameter: M3 screw is φ6.0+0.2mm, crater diameter φ10.0mm;
² M2.6 screw is φ5.0+0.2mm, and diameter of crater is φ9.0mm.
² Thickness of wishbone and peribone root: 1.2+0.2mm.
² Thickness of top RUBBER cross bone of button: 0.9+0.1mm.
² Wall thickness at the top of column: 1.2±0.1mm.
² Glue thickness of crochet position of rear mold of battery box is less than 2.0mm.
Injection Mold 
² Misalignment of plastic part is less than 0.05 mm when front and rear molds are on same PL surface.
² Face and bottom case fit.
A. Secondary or tertiary seam fit requires that misalignment of PL surface is less than 0.1 mm, and there is no scratching phenomenon;
B. Unilateral gap between seam and bag is 0.1-0.3 mm, and larger value is taken if shape is complex.
² Horizontal unilateral gap between battery door and battery box is 0.2-0.3 mm.
² Button matches hole. Unilateral gap between button and hole of general geometric shape is 0.15-0.25 mm. One-side gap between special-shaped button and hole is 0.3-0.4 mm, gap between fuel injection button should be larger. When button and flower are matched, cooperation can meet safety test standard.
² Matching card slots. Unilateral gap between card door and bottom case is 0.2-0.3 mm. Unilateral gap between socket and plug box is 0.5mm.
² Minimum clearance on one side of axis of four major parts is 0.1-0.2 mm.
² Unilateral gap between LOCK and matching pillow hole is 0.2 mm.
² Unilateral gap between bracket and its matching hole is 0.1-0.2 mm, and larger value is taken if length is greater than 150mm.
² One-side gap between COVER and its matching hole is 0.1 mm.
² Unilateral gap between ROLLER and its mating hole is 0.5-1.0 mm.

(2) Surface defects (when process conditions cannot be met)

1. Defects are not allowed on the surface of plastic parts.
A. Glue is uneven (or lack of material, stagnant water) B. Burnt C. Top white D. White line E. Peaking F. Bubbling G. Whitening (or cracking, breaking) H. Baking I. Wrinkles
2. Surface limited defects and acceptance.
A. Strength of water mark can pass functional safety test.
B. Generally, length of water mark in perforated hole is not more than 15 mm, and water mark in round horn hole is not more than 5 mm.
C. Length of water lines at fusion of multiple nozzles is not more than 20 mm.
D. Water lines on the wrist are not in the middle of wrist or where force is applied.
E. Outer surface of plastic part corresponding to column position has no water marks.
F. Key bracket with fire pattern on the surface has no water marks.
G. Water lines of internal parts are not restricted at the position where strength allows.
<2>. Shrunk
A. Slight shrinkage is allowed at inconspicuous position on the surface of plastic part (no dents can be felt).
B. Internal parts may shrink slightly if size allows.
C. Non-appearance surface of plastic part does not affect size, and shrinkage under strength is not limited.
<3>. Drag white
A. Slight whitening is allowed on the side of plastic parts with fire pattern or sun pattern, and can be eliminated by processing with abrasive paste.
B. Appearance of plastic part has no whitening on the first side.
<4>. Deformation
A. Unevenness of supporting feet of larger bottom shell is less than 0.3mm.
B. Unevenness of KEY bracket is less than 0.5mm.
C. Deformation of plastic parts should be adjusted and controlled by rack after molding.
D. Except for above items, there is no deformation of plastic parts.
<5>.Air mark
A. For plastic parts made of PE, PA, PVC, PC and other rubber materials, slight air marks are allowed at nozzle position. Air pattern does not protrude from nozzle by 3.0mm.
B. For dolls with thick and uneven wall thickness, slight air marks are allowed at nozzle position and engraved protrusion.
C. In addition to above two items, there is no air mark on the surface of plastic part.
<6> yellow gas
A. Larger bottom shell with water entering in the middle; slight yellow gas is allowed near nozzle, degree of yellow gas should not affect natural color of plastic part, and only slightly change color depth.
B. Except for above cases, there is no yellow gas in plastic parts.
<7>.Nozzle residue
A. There is no interference in position of nozzle of plastic part and residue during assembly.
B. There is no glue and feces at nozzle position, and film is submerged into water without thimble position.
C. There are no traces of nozzles on appearance surface of plastic parts after assembly.
<8>.Snake pattern
A. There is no snake pattern on appearance surface of plastic parts after assembly.
B. Serpentine patterns are allowed on internal parts or non-appearance surfaces after assembly if they cannot be improved.
<9>. Pointed, thin plastic parts
Except for plastic parts such as piano keys that are allowed to have specially designed sharp and thin rubber parts, other rubber parts have no sharp and thin rubber parts.

(3) Surface modification requirements

1. Surface highlights.
² High-gloss surface should be smooth and have a mirror effect;
² Non-appearance surface of front mold surface and internal parts are allowed to have slight processing traces on the surface.
² Defects such as scratches, rust, and spots are not allowed on high-gloss surface.
2. Surface decoration (EDM or drying pattern).
² Texture meets design requirements, texture should be uniform and sides should be consistent with surface.
² Mutual accessories require consistent texture. (except those matched with old parts)
3. Surface font.
² Height of font on the surface meets design requirements and must be uniform.
² Font width, size, density, word count, and position meet film requirements.
4. Modification of CORE surface.
² Generally, CORE surface needs to be light-saving, without obvious spark marks and tool marks, except for special requirements.
² Appearance of transparent plastic parts or after assembly meets design requirements

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