Injection Molding regulations.

In the process on constructing the crocodile clip on solid works and considering the process of injection molding as there is quite a few key points to considering during the phase while doing it on the software.

So far we currently have gathered that the production process of the existing clips in the market available are injection molded. Reasons for these types of production being ideas for mass production are as it produces huge amount as a cheap and easy way while remaining as a profitable piece towards the industrial end for the company.

Having the outer clip produced from plastic is a trendy manufacturing process at the moment were its easy to produce and very cost efficient.

During the production phase, aspects that need to be considered in injection molding are:

Draft angles

Parting lines

Sink marks

Draft angles-

Draft facilitates the removal of the part from the mold and is very important in injection molding where the molds are straight pull only (no side actions).

Here are some rough guidelines to follow:

At least 0.5 degrees on all “vertical” faces

2 degrees works very well in most situations

3 degrees is minimum for a shutoff (metal sliding on metal). Without this, the
mold would lock up and be unable to open

5 or more degrees is required for heavy texture

Pointers to consider during the rendering process of the clip.

Parting lines-

Is the line of separation on the part where the two halves of the mold meet.

It indicates the plane part that passes through the part.

Parting lines cannot be avoided, every part has them.

The melt will always flow towards the parting line because it is the easiest place for the displaced air to escape or “vent”

These flash lines are allocated towards the sides of the clip allowing for no inference of the motion of the clip.

Sink marks-

When the hot melt flows into the injection mold, the thick sections don’t cool as fast as the rest of the part because the thicker material becomes insulated by the outside surface of faster cooling plastic. As the inner core cools, it shrinks at a different rate than the already cooled outer skin. This difference on cooling rates causes the thick section to draw inward and create a sink mark on the outside surface of the part, or worse, completely warp the part. In addition to being unattractive, the mark also represents added stress that is built into the part.

This part that will be a consideration during the measurement part of drawing up the mold on solid works and taking in account of the wall thickness.

One way to avoid sink marks is to core out the solid sections of the part to reduce thick areas.


ABS, polypropylene or polyethylene as it is the cheapest, most effective way of producing these clips in large quantities. The current method for producing the crocodile clips and has proven to be a durable method with ABS.  Injection moulding has a lot of regulation and guidelines mostly revolving around draft angles for easy removal from the mould and material thickness to prevent shrinkage in the part. Considering there are so many regulations surrounding injection moulding.

Flash lines


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