Surface Finishing Aluminium

Stage 1 (Lapping) Equipment used:

• Kemet 24” lapping machine
• Cast Iron lapping plate
• Kemet Flatness gauge
• Kemox 0-800s

Stage 2 (Polishing)

• Kemet 24” lapping/polishing machine
• ASFL polishing cloth
• 3 Micron type k diamond slurry

Process breakdown for polishing Aluminium light housings

Stage 1: All parts were spaced equally depending on quantity in a 24” control ring. A dycem backed 4kg pressure weight was place on top to act as a fixture. The machine was cycled on a flat cast Iron lapping plate with kemox 0-800s being applied by the abrasive pump for 5-10 minutes. They were then taken and cleaned off with Co42 cleaning fluid.

Stage 2: The cleaned up parts were then placed into a plastic faced control ring with a 4kg pressure weight placed on top. The machine cycled for 5 minutes on an ASFL polishing cloth with 3 micron type k diamond slurry being dispensed at a ratio of 2 seconds of spray ever 40 seconds. Parts were then cleaned with Co42 cleaning fluid.

Stage 1

• Machine Type: Kemet 15 lapping/polishing machine
• Lap Plate: Cast Iron
• Abrasive Type/Grade: Kemox O-800S Aluminium oxide premixed slurry

Stage 2

• Machine Type: Kemet 15 COL-K Polishing machine
• Polishing pad: MRE short nap cloth
• Abrasive Type/Grade: Col-K (NC)

Process breakdown for Aluminium

We have selected a CMP process for the final polishing as this uses a chemical action to polish the surface of the components in place of a conventional abrasive type polishing process. This means that there should not be any abrasive left in the surface of the Aluminium. The polishing time was 80 minutes using the set-up that we had available for the parts, but with the addition of extra pressure this could be reduced.

Resulting Ra from this process: Ra 1.647µinch

Component Details: Small Aluminium heat sink

Stage 1 (Grading stage)

• Machine Type: Kemet 15” 3 ring conventional lapping machine
• Lapping Plate: Cast Iron
• Abrasive Type/Grade: Kemox 0-800 Fine

A cast iron plate with Kemox 0-800 Fine Aluminium Oxide slurry was used to give the component a flat matt finish prior to polishing. The length of this stage depends upon the surface finish before lapping begins.

Stage 2 (Pre-polish)

• Machine Type: Kemet 15” 3 ring diamond lapping machine
• Lapping Plate: ASFL-AW silk cloth
• Abrasive Type/Grade: 3micron Type K STD diamond slurry

An ASFL-AW silk cloth with 3micron Type K STD diamond slurry was used to pre-polish, this produced a good reflective finish.

Stage 3 (Mirror Polish)

• Machine Type: Kemet 15” 3 ring diamond lapping machine
• Lapping Plate: Chem Cloth H
• Abrasive Type/Grade: Col-K

Finally a Chem Cloth H with COL-K was used to mirror polish. This produced a blemish free finish.