Tips and Trick Designing to avoid sink mark

Since we have recomended formula to avoid sink mark t <=1/3 T

We should consider rib thickness when designig reinforce rib or hook, boss which can make void or sink mark at plastic product.

Why sink mark should be avoid from plastic product? Sink mark is one of many plastic part defect, it can be goup in appearcne defect. it make ugly appearance when defect occure on your product.

How to designing it?

Here is the best practice design.

Boss Feature

for short boss we can apply thispractice.

below is recomnded design for high boss with make undercut feature (need angular mechanism).

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Plastic Product Design

First step in product designing is understand about customer needs,  whatever product will be create.  Without customer needs it's difficult to make our product can sold out to customer. 

There is so many factor should be consider to product designing, especially in plastic product.  It's needs carefully, high skill, high ability, also an designer experience at collection customer needs data.

Specification and requirement from customer is main keys for designing plastic products, the customer always want to his product have good quality and have good price.   There is other factor as designer consideration to design product:

1. Product Function
2. Product manufacturing 
3. Cost and aestetica

That factor become references in product designing,  there is attention to designer because a little mistake make difficult to create molding or dies and possible to redesign it's product.

• Product Function

A Products can succes in the market if it's have good selling points and have good function and of course the advantages.  A designer have a free imagination for creating products, but a designer must consider about function becouse without good function, the product is no meaning.

• Product Manufacturing

There is so many way a product processing.  There is casting, Dies, Molding, Ijection Molding, Blow Molding, Die Casting,  etc.   Plastic product can produce using injection method, injection molding or blow molding.

There is some rule to be attention for design engineer:

1. Wall Thickness,
2. Parting Line (P/L)
3. Shape Corner
4. Draft Angle
5. Cross section area
6. Rib

Wall Thickness

Wall thickness of plastic part should be keep uniform, if there is different wall thickness, it should be not extremly different. The advantages of uniform wall thickness is when injection process (filling step will easier than un-uniform thickness),  can reduce defect plastic part such as void, sink mark, warpage.

Parting Line

Parting line is line mark at product injection cause by separation between core and cavities of mould.  This parting line some times make defect calls flashing. This defect make product have sharp line, so parting line design should be hidden from appearance or operator (customer) to avoid injured at operating product by customer (claim will happened).

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