Mold Tech

Plastic mold polishing

• 2021-08-13

There are normally two ways to do Plastic mold polishing:

1. Do it in-house.

When we do the mold polishing in-house we could keep the time control.  And will be easy to communicate with your polishing department to keep the high-quality polishing job, this will prevent the issue happened by the over-polishing jobs.

2. Do it outsource.

• You still can take control of the lead time easier by scheduling the polishing to an outside polishing company. Especially for some multiple cavities molds, because they have many polishing workers and can work on polishing cavities separately.

• But when meet some issue that will be difficult to discuss with each other, if your polishing supplier is close to you, that will be much easy, you can go over there in minutes and explain to them

Final suggestion to handle the mould polishing works

1. For some surface if your customer needs texture surface to cavity side, you can work this use EDM machine to make surface texture directly, This is my favourite method, because almost all the works are finished by EDM jobs, the advantage on this is when the draft angle is very small and cavity side need some textured surface, use EDM you will never get any scratch issue, and this will be the only way to prevent the quality, we have been done this many times, at the first beginning we used the old way ( polishing and then texture), the was scratch issue on some area and never solved, finally we made a new cavity and made with texture by EDM machine, the result was perfect.

2. For some mold the cavity side needs high gloss polishing surface, which means this is high gloss plastic molding parts, so EDM machining is not possible to get mirror polishing surface even EDM machine can get the high gloss surface, but for some requirement are too high to meet, in this case we have to do the high polishing jobs, the best way to solve this is outsource, to find the professional polishing company to manage this hard task.

Tips to improve your plastic mold polishing

• Cleanliness. Keep your polishing area away from grinding dust and chips. Do not allow it to become a disorganized mess of loose stones and accessories.

• Separate your stones. It is amazing that people dump a 220 gritstone in a box or can with a 600 grit stone. Sometimes they even mix up polishing sticks with different grits of the diamond. Let’s see, if you think you are polishing with a fine finish diamond and you get a coarser diamond piece mixed in, what do you think will be the result?

• Move your polishing area away from grinders and bead blasting equipment. For some reason, many shops just keep polishing away, right next to the surface grinders. All it takes is one stray piece of grinding grit to ruin your finish.

• Use a microscope. Even though it is disheartening to see your work under a microscope, this is the only way to see the tiny scratches and imperfections. Plus, you can avoid rolling edges and damaging critical molding details

• Don’t use unskilled help to do skilled work. Polishing is an art that takes a lot of time to learn. Don’t expect everyone to have the same ability when it comes to fine finishes or detail. Yet this often happens when owners view polishing as a nuisance.

• Make a chart of the diamond paste colors. For some reason, some shops never write down which diamond is which grit and moldmakers are left trying to figure out the same problem over and over again. Figure it out and make a copy near the diamond compound!

• Don’t think that “cross-hatching” is some kind of religion. Sometimes you see people who think you must only polish in one direction for each grit. Horizontal with a 400 grit and vertical with a 600 grit, for example. You can and should go back and forth in any direction you need to, just make sure you end up with the lines in the direction of the ejection-draw polish it. Your speed will dramatically increase once you get over this misconception.

Hope this information is helping you on how to do better mold polishing, in this case, you could have a better idea on your project what kind of surface will be the best option, any question welcome to send us an email

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