Plastic Injection Molding Design Guides:-

This design guide for plastic injection molding may be helpful to an experienced design engineer or one  just starter with injection molding.

@ basic principles of injection molding and benefits , limitations and applications. 
@Optimize your parts for plastic injection molding
@Consideration to reduce cost of your future projects
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Selection of plastic injection tool

Prototyping tools

Tool shot life - arond 1k
shorter manufacturing time
Cost efficient in mold only, but higher cost at high volume molding run.

Production tools

Tool shot life-100k to 1M shots
longer manufacturing time
Cost efficiency at higher volume, mostly at automatic production.

​Selection of plastic injection molding materials
​Plastic Materials  & Properties

ABS, PC, HIPS                             Cosmetic
ABS, PMMA, PVC, PE, PC        Impact Resistance
POM, PEEK                                 Wear Resistant
PP, PE, PA,PEEK                         Chemical Resistance
ABS,PPS,HIPS,PBT                    Dimensional Stability
PP, HDPE, LDPE                        Cost economy
TPU,TPE,Silicone                       Rubbber feel

                                         Recommended Wall Thickness

                              Only reference for general thickness with a molded part. Specific part geometry, say ribs, will affect thickness.

MOLDS  and PARTS  identification

Each cavity is marked with the number or letter.
It will be applied for molds with more than 1 cavity.
Proposal of marking area will be sent to you  before mold production. 

Injection moulding surface finish 
It is critical to a successful part design and used for aesthetic and functional reasons.
Two main standards: VDI 3400 ,  SPI 

VDI  3400 surface finish

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SPI  surface finish

There are 12  SPI  fnish grades of which can be achieved by below methods:
SPI   A1, A2, A3    Grit Diamond (high gloss)
SPI   B1, B2, B3    Grit Paper (semi-gloss)
SPI   C1, C2, C3    Grit Stone (low gloss)
SPI   D1, D2, D3   Dry Blast (Matte) 

Steel selection GUIDE for surface finish

To achieve mirror fnish, you need to start  from dull finish and by experienced  mold steel tooling  polishers. 
Selection of steel is also a critical issue as steel grains quality affect feasible achievement.

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