5 Ways to Resolve Injection Molding Sink Marks

Are you an injection molder with a sinking feeling when it comes to sink marks on your parts? Never fear, because we’ve got five great solutions that’ll put the bounce (or lack thereof) back in your project! You don’t need a sea captain to ensure that no sink marks will plague your next injection molded part – we’ll show you how easy it is when you know what causes them and how to prevent or fix them. So come aboard our ship of knowledge and let’s set sail against sunken projects today.

Injection molding sink marks can be enough to give any engineering manager a headache. But no need to panic; there are some easy fixes for overcoming this injection molding nemesis. 

optimize part temperatures, adjust the core and cavity vents, increase injection speed, reduce pressure during injection, and use longer gates. In doing these things with precision and care, you should see an end to your Injection Molding Sink Mark woes.

What are injection molding sink marks and what causes them?

Injection molding sink marks are like the dimples on a golf ball, but decidedly less charming! In essence, they are small depressions or hollows that appear on the surface of a plastic part after the injection molding process is complete. 

In most cases, these unsightly molds result from too little clamp force being used during the injection phase and less than ideal cooling conditions, leading to uneven shrinkage. In other words, too much heat makes things go south – literally! So if you want your parts to come out looking as good as they should be, make sure you’re using enough clamp pressure during injection and implement suitable cooling measures.

How do you prevent sink marks and voids?

Injection molding is a remarkably efficient process. It can help manufacturers of all sizes quickly produce parts from almost any material imaginable, including plastics and metals. But the injection molding process does have its drawbacks: notably, sink marks and voids. 

Fortunately, there are ways to lessen their presence! In terms of sink marks, one should consider increasing injection speed and pressure or using specific nozzles designed to prevent them. In terms of voids, using a proper gate location and size and fillers might help cut down on their appearance as well. In summary, with quick reflexes and careful calculations, you can throw that faulty sink mark and void combo right out the window!

5 Techniques for Resolving Injection Molding Sink Marks:

Injection molding can be a tricky process, but have no fear! There are 5 surefire ways to get rid of those pesky Injection Molding Sink Marks. 

• Injecting additional material into the part during molding, 

• Using greater injection speeds or pressures, 

• Moderating dwell times and cooling slices, 

• Reducing wall sections 

• Creating draft angles 

These tricks will have you wishing Injection Molding Sink Marks was your last problem. Follow these steps and you’ll be able to make Injection Molding Sink Marks disappear faster than you can say “Abracadabra!”

Sink Marks and DFM:

Injection molding is a complex yet precise process, which can be made more precise with the help of Design for Manufacturing (DFM). In particular, DFM aids in preventing sink marks – those pesky imperfections that make your piece look like Swiss cheese. Many variables can cause these indentations, from an inadequate gate size or insufficient cooling time to using the wrong resin material. But by carefully considering these factors in the design and manufacturing phase, you can reduce the occurrence of sink marks – and have a good looking injection molded piece without sacrificing functionality.

Sink Marks Cause- High Mold Temperature:

Injection molding sink marks can happen for a variety of reasons, but often the root cause is simply a case of “too hot to handle.” In other words, the mold itself needs to be kept at a relatively cool temperature compared to the melted plastic that’s being injected into it. 

If the mold gets too hot, it can’t keep up with cooling down the plastic before it starts to solidify and you’ll end up with those dreaded sink marks on your parts. So remember to keep your molds and your expectations in check – allow for plenty of cooling time, or you might be left feeling burned.