Mold Polishing Tips For Injection Molds

 

Mirror polish injection molds

 

What is mirror polishing?

Mirror polish injection molds refer to molds that have a highly reflective and smooth surface finish, similar to a mirror. This is achieved through a polishing process that removes any surface imperfections and creates a high-gloss finish.

Mirror polish injection molds are often used in applications where the final product requires a high level of clarity, such as in medical devices, optical lenses, and consumer electronics. The mirror-like finish helps to reduce the amount of light scattering and distortion, resulting in a clearer and more precise image.

The polishing process for injection molds is typically done using a series of abrasive compounds and polishing tools, starting with a coarse grit and gradually moving to finer grits until the desired level of mirror finish is achieved. The process can be time-consuming and requires a high level of skill and expertise to achieve the desired result.

Overall, mirror polish injection molds are a valuable tool for producing high-quality products that require a clear and precise finish.

[caption id="attachment_4629" align="alignnone" width="300"] Mold Polishing[/caption]

Mold Polishing Tips For Injection Molds:

① Surface after the rough polishing process by milling

EDM, grinding, etc. You can choose the speed at 35 000-40 000 rpm rotating surface polishing machine or ultrasonic grinding machine for polishing. Commonly used methods using diameter Φ3mm, WA # 400 wheel removing layers of white sparks. Then hand Whetstone grinding, strip Whetstone plus kerosene as a lubricant or coolant. The general order of use is # 180 to # 240 to # 320 ~ # 400 ~ # 600 ~ # 800 to # 1000. Whetstone polishing method. Which is the most important job a difficult job processed according to different specifications? And an angle of approximately 70 degrees a balanced cross lapping position? Ideally from a range of about 40 mm to 70 mm. Whetstone jobs will vary according to the material processed. Many mold manufacturers in order to save time and choose from # 400 to start.

② Semi-fine polishing semi-fine polishing mainly used sandpaper and kerosene.

After Whetstone's job is job sandpaper, sandpaper when the job. Pays attention to die Jen rounded edges, rounded corners, and orange peel generation. So try to make the finest Whetstone flow processing. Sandpaper polishing focus. Sandpaper with a hard stick like a stone like a job for about 70-degree angle to cross grinding. Polishing sandpaper side number about 10 times to 15 times. If the grinding time is too long, the grinding force of sandpaper will reduce. Which would lead to the machined surface uneven phenomenon? Which is also produced one of the reasons orange peel?

When jobs are generally used bamboo sandpaper grinding. Low stretch material actually used a small stick or rod hardness of about 45-degree angle grinding is the most ideal. The polished surface cannot be used as a rubber or a material with high elasticity. And cannot be polished with a 45-degree angle may be an acute angle shape. Numeral sandpaper as follows: # 220 ~ # 320 ~ # 400 ~ # 600 ~ # 800 ~ # 1000 to # 1200 to # 1500. Actually, # 1500 sandpaper only suitable for hardened tool steel (52HRC above) does not apply to pre-hardened steel. This may lead to pre-hardened steel surface burns.

③ Fine polishing diamond polishing paste mainly used.

If the powder or mixture of diamond abrasive grinding wheel pastes for polishing a polishing cloth. Then the order of the normal polishing 9μm (# 1800) ~ 6μm (# 3000) ~ 3μm (# 8000). 9μm diamond polishing paste and polishing cloth wheel can be used to remove the # 1200 and # 1500, leaving hair like sandpaper grinding marks. Then with sticky carpets and diamond polishing paste for polishing. The order of 1μm (# 14000) ~ 1 / 2μm (# 60000) ~ 1 / 4μm (# 100000).

Accuracy requirements in 1μm above (including 1μm) polishing process in the mold processing workshop in a clean polished interior can be carried out. If a more precise polishing an absolute necessity to clean the space. Dust, smoke, dandruff. And saliva Mo is likely to be scrapped after a few hours of work to get a high-precision polishing surface.

Cn-moulding is a reusable china injection mold company. We focus on high glossy mold manufacturing. One strong point of us is polished mold mirror and glossy, with short cycle time and competitive price.

Why injection molds use hot runner?

 After years of development, injection molds have become one of the preferred molds for manufacturing in all walks of life around the world, especially in the developed countries of Europe and the United States, which have advanced in the industry. The most important thing to mention is the use of hot runner technology in injection molds.

hot runner

1， Hot runner technology shortens the injection molding cycle

Because there is no limitation of the cooling time of the main channel and the secondary flow channel, the injection mold can be ejected in time after being solidified. Many thin-walled product molding cycles produced with hot runner molds can be completed in less than 8 seconds.

2，Eliminating subsequent processes is conducive to production automation.

After the workpiece is formed by the hot runner mold, it is the finished product. There is no need to trim the gate and recycle the cold glue lane. Conducive to production automation. Many foreign manufacturers have combined hot runners with automation to significantly increase production efficiency.

3， Hot runner technology saves plastic raw materials

In the traditional mold injection, the nozzle material is produced. The high plastic product is not allowed to use the water material (recycled secondary material). Because the reuse of the nozzle material will degrade the structure and performance of the plastic part, the reuse will affect the product quality. There is no cold runner in the hot runner mold. So no nozzle material is produced (fees are required). This is especially significant for applications where the price of plastics is expensive. In fact, the major hot runner manufacturers in the world have experienced rapid development in the world. When oil and plastic raw materials are expensive. Because hot runner technology is reducing materials and reducing materials. Fees, an effective way to save costs.

4，Expand the application of the injection molding process

Many advanced plastic molding processes have been developed based on hot runner technology. Such as PET preforming, multi-color co-injection in the mold, a variety of materials co-injection process

5， Reduce the defective products of injection molds and improve product quality

During the hot runner mold forming process, the plastic melt temperature is accurately controlled in the runner system. The plastic can flow into the cavities in a more uniform state, resulting in a consistent quality plastic part. The hot runner molding plastic parts have good quality, low residual stress after demolding, small deformation of plastic parts. And greatly improved the surface appearance of injection mold products. Therefore, many high-quality products on the market are produced by hot runner molds. Many familiar plastic parts, such as telephone casings, mobile phone cases, printer cases, computers, and automobiles, are produced using hot runner molds.

The factors affect the percentage of regrind materials

 

The factors affect the percentage of regrind materials

The factors affect the percentage of regrind materials

1, The purpose: In order to control and improve the quality of plastic parts, reduce the cost of plastic parts and injection molding plant regrind materials management, to meet customer technical requirements.

2, The scope: for the injection of all of the Company ABS, PA66, PA6, PP plastic parts, and workshop back to powder, processing, storage, labeling, and other management regulations.

3, Regrind material recovery and grade classification

1, Recyclable materials:

A.Defective products produced during injection molding (such as scratches, incomplete, burr) and other defective products.

B, injection molding process generated in the runner compound (nozzle material).

C, other (such as: engineering testing and other models can not be shipped demolition of plastic pieces or scrap pieces).

2, Regrind materials level:

A, The first regrind materials: the new material produced by the first injection of plastic.

B, The second regrind materials: after the second injection of plastic produced.

C, The third regrind materials: the second or more (including three) after injection of plastic and scrap.

The bulk density of the regrind is probably the single biggest factor affecting how much regrind one can use.

If you are using a recycled film scrap that hasn’t been densified then you pay a tremendous penalty in your rate. There are densifiers like a Munchy that will compact the film scrap to something close to a virgin pellet. In this case, then you can use quite a bit of scrap – 20 – 30%.

Another thing affecting your percentage of regrind is the use of grooved feed sections for extruders. They really are not designed for anything but pelletized material. It is best not to use more than 5% regrind if you have a grooved feed otherwise the grooves will clog and production rate will drop significantly and product quality will also suffer.

In blow molding, for instance, it is not uncommon for bottlers to use 35% regrind as the moels and tails comprise a considerable amount of material in relationship to the end product. That stuff is usually compressed and put back in the hopper.

Pre-hot runner systems had a lot of regrind as dense material sitting in the runners and gates was recycled. Those rates were quite high. I have seen that as high as 50%.

The other points are quite well such as contamination from streams and other things that need to be considered. In the end, I would say there is NO rule of thumb it greatly depends on so many factors.

There is no 1 rule of thumb. It will depend on several elements;

What type of Polymer and how they degrade (heat stability and moisture content)

whether filled and type of filler. Glass length will degrade making more brittle, lower modulus

whether it is a blend, PC: PBT interact with each other (transesterification)

can you add heat stabilizers, can increase the level of regrind

what kind of shear are you putting into the mix

you won’t try to color match or all bets are off on color stability

Ultem PEI is great, but high heat, I’ve seen >50% regrind work fine, unfilled PP of PE can go a long way with the addition of phosphate/phenol stabilizers.