Polishing and brushing for aluminum and zinc die casting products
Polishing and brushing are commonly used as pretreatment for further surface treatments like painting or electroplating. Besides, special polishing such as mirror polishing can also be used as decoration means. Usually, after mirror polishing, the aluminum casting parts will be slightly lacquered to protect the shining surface appearance. General speaking, some decorative parts by aluminum die casting is likely to apply for mirror polishing, such as furniture parts, showing room products, or automobile handgrips.
Parison die casting has set up our own polishing and brushing workshop with cooperation of other factories. Because of porosity of aluminum high pressure die casting parts, there is high rejection rate in polishing and brushing process especially in mirror polishing. Therefore a professional polishing team is essential to control quality.
Mirror polishing is likely applied for die cast decoration products such as die cast furniture products, display parts etc. The mirror polished die castings are always required for further lacquering. Because the polished surface is subject to oxidization in atmosphere leading to gray and ugly surface.
Compared with aluminum die casting parts, zinc die casting products are preferred to mirror polishing. For zinc die casting parts are always used for decoration purpose. In order to achieve fine mirror polished surface and reduce rejection rate, we always use large tonnage die casting machine to cast rather than regular tonnage machines so that density of the die casting can be higher than that in common production situation.
Brushing is to work out slight brushing lines on aluminum or zinc die cast work pieces just as a decoration means. Brushing can be used alone or with lacquer protection afterwards. It is popular for die cast furniture parts or appliance housings.
The most application of brushing is using with nickel plating. Brushing can be made before nickel plating to achieve coarse brushing line and saving nickel consumption. The other ways is brushing after plating to carry out very fine brushing line which is always used for die cast door handles , zinc die cast medals etc.