Design Guidelines: Plastic Injection Molding

Our basic guidelines for plastic injection molding include important design considerations to help improve part moldability, enhance cosmetic appearance, and reduce overall production time.


Size

Maximum Dimensions

SIZE 18.9 in. x 29.6 in. x 8 in.
VOLUME 59 cu. in.
DEPTH 4 in. from parting line
Up to 8 in. if parting line can pass through the middle of the part
PROJECTED MOLD AREA 175 sq. in.
SIZE 480mm x 751mm
VOLUME 966,837 cu. mm

DEPTH

101mm from parting line
Up to 203.2mm if the parting line can pass through the middle of the part
PROJECTED MOLD AREA 112,903 sq. mm

Typically, China Metal Parts can maintain a machining tolerance of +/- 0.003 in. (0.08mm) with an included resin tolerance that can be greater than but no less than +/- 0.002 in./in. (0.05mm/mm).

 

 

Materials

  • ABS
  • ABS/PC
  • Acetal
  • Acetal Copolymer
  • Acetal Homopolymer
  • ETPU
  • HDPE
  • LCP
  • LDPE
  • LLDPE
  • Nylon 6
  • Nylon 5/12
  • PBT
  • PC/PBT
  • PEEK
  • PEI
  • PET
  • PETG
  • PMMA
  • Polycarbonate
  • Polypropylene
  • PPA
  • PPE/PS
  • PS

VIEW MATERIALS >


Surface Finishes

FINISH DESCRIPTION
PM-F0 non-cosmetic, finish to China Metal Parts' discretion
PM-F1 low-cosmetic, most toolmarks removed
PM-F2 non-cosmetic, EDM permissible
SPI-C1 600 grit stone, 10-12 Ra
PM-T1 SPI-C1 + light bead blast
PM-T2 SPI-C1 + medium bead blast
SPI-B1 600 grit paper, 2-3 Ra
SPI-A2 grade #2 diamond buff, 1-2 Ra

Custom Color Matching & Secondary Finishing Options

Custom color matching is offered on customer-supplied Pantone numbers and customer-supplied part samples.

Mold texturing applies industry standard textures to a mold and you can expect the equivalent of a Mold-Tech finish.

Threaded inserts are possible through secondary heat staking and ultrasonic welding processes. A complete chart of stocked inserts is available here.

Pad printing transfers a two-dimensional image like company logos onto a three-dimensional object.

Laser engraving is applied to the mold or directly to final parts for information such as part numbers.

Basic assembly includes fastening molded parts together that we’ve manufactured and/or applying of labels to individually bagged parts.

VIEW ALL FINISHING OPTIONS >





Draft

VERTICAL FACES
0.5°
MOST SITUATIONS
MINIMUM FOR SHUT OFF
MINIMUM FOR LIGHT TEXTURE (PM-T1)
MINIMUM FOR LIGHT TEXTURE (PM-T2) 5°+

Undercuts

 Maximum Side Core Dimensions

WIDTH HEIGHT PULL
< 8.419 in. < 2.377 in. < 2.875 in.

 Maximum Side Core Dimensions

WIDTH HEIGHT

PULL

< 213.84mm < 60.38mm < 73.66mm

Wall Thickness

MATERIAL RECOMMENDED WALL THICKNESS
ABS 0.045 in. - 0.140 in.
Acetal 0.030 in. - 0.120 in.
Acrylic 0.025 in. - 0.500 in.
Liquid Crystal Polymer 0.030 in. - 0.120 in.
Long-Fiber Reinforced Plastics 0.075 in. - 1.000 in.
Nylon 0.030 in. - 0.115 in.
Polycarbonate 0.040 in. - 0.150 in.
Polyester 0.025 in. - 0.125 in.
Polyethylene 0.030 in. - 0.200 in.
Polyphenylene Sulfide 0.020 in. - 0.180 in.
Polypropylene 0.035 in. - 0.150 in.
Polystyrene 0.035 in. - 0.150 in.
Polyurethane 0.080 in. - 0.750 in.

 Table is adapted from manufacturingcenter.com.

MATERIAL

RECOMMENDED WALL THICKNESS

ABS

1.143mm - 3.556mm

Acetal

0.762mm - 3.048mm

Acrylic 0.635mm - 12.7mm
Liquid Crystal Polymer 0.762mm - 3.048mm
Long-Fiber Reinforced Plastics 1.905m - 25.4mm
Nylon 0.762mm - 2.921mm
Polycarbonate 1.016mm - 3.81mm
Polyester 0.635mm - 3.175mm
Polyethylene 0.762mm - 5.08mm
Polyphenylene Sulfide 0.508mm - 4.572mm
Polypropylene 0.635mm - 3.81mm
Polystynene 0.889mm - 3.81mm
Polyurethane 2.032mm - 19.05mm

 Table is adapted from manufacturingcetner.com.


Radii

Some part corners will have a radius rather than a sharp edge since we use an automated CNC milling process to make the mold for your parts. This typically does not require a change to your model, but resulting radii are identified before the mold is milled.


press operator examining plastic injection molding part

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