Where theworld gathers for metal finishing
Q&As since 1989
-----
Unable to achieve finish
Q. I work with a company which is in the business of Sourcing Automotive components from Indian as well as overseas suppliers and supply them world wide.
Recently we have bagged an order from an European firm for aluminum die cast component. This part requires Shot blasting before machining. We have tried everything to match the finish of the Italian sample for the luster , But are not successful. We match the Ra value but our casting comes out dullish in finish as compared to the European sample. To give you a better picture, if the European sample is silver-ish in luster our component comes out Light silver gray . This is not acceptable to our customers.
On talking to our European customers they say the process is SAND BLASTING.
I would be highly obliged if you could assist me in finding out a solution to this problem.
Regards,
Hoping for your reply.
Rahul Sharma- Pune, Maharashtra, India
A. There is a difference between shot blasting and sand blasting. I find it hard to believe that they actually use sand as the blasting media. Sand is inefficient and normally can't be recycled more than 2 or 3 times. I think that maybe they are just using the generic terminology. I suspect they are using glass bead media which produces a nice high gloss finish. You might ask them again to clarify actual media and ask them for specs on media.
AF Kenton
retired business owner - Hatboro, Pennsylvania
A. Blasting with white corundum will give you a silver finish on aluminium castings. You may find this material from abrasive manufacturers.
Jatin Thakkarinvestment castings - Sihor, Gujarat, India
A. I agree with Mr AF Kenton said. The solid glass beads (micro glass beads) of size: 212 to 106 microns with 90% of true spheres would provide the bright silver dull finish. That is what is needed. The pressure should be 40 PSI.
Kishore Dagaglass beads - Chennai, Tamilnadu
Q. Well, we are using Steel Shot and Grit Mix to achieve the desired colour and finish on the die casting products, but during machining (drilling, tapping) and impregnation process, many stains are left over on the components and all the efforts of getting good finish go in the drain.
We end up doing PU coating on the components, but the cost and time consumed is very high.
Even the Wet blasting with glass bead, brings good satin finish, but the process and transportation cost is much higher.
I was thinking of installing an ultrasonic cleaning machine ... I do not know if it will help?
- Delhi, INDIA
April 16, 2012
Q, A, or Comment on THIS thread -or- Start a NEW Thread