Aluminium Tooling Finishes

Types of Tooling Finishes

Finishes for aluminium tooling can be a crucial element when it comes to ensuring the quality, functionality, and finish of the final injection moulded parts.

While finishes for aluminium tooling may not always be necessary, an aluminium tool will sometimes require a particular finish. Whether a finish is necessary, and indeed what type of finish, will be largely dependent upon the type of plastic injection moulded parts that are required from that tool. 

Determining factors include such things as the final component’s intended application, its cosmetic requirements, and its performance needs.

At RP Technologies, we provide a variety of options for finishes on our aluminium tooling. These include texturing, engraving, graining, polish, bead blasting, and VDI finish.


Texturing/graining can be employed to achieve highly cosmetic finishes such as interior grains. This type of finish can be employed in the automotive sector at OEM standards. 


Engraving of part numbers, logos, and cavity ID’s is commonplace, as along as space is available within the tool for this be completed via a CNC process. Where this isn’t possible, it may be feasible to laser etch these details.


Polishes vary from removing cutting marks from CNC machining on a tool, to a commercial polish (600 grit), and a mirror high diamond buff polish.

Bead blasting

Tooling is polished to a 400 grit finish. It is then textured by blasting it with medium sand or glass bead. This gives a mottled effect to the tool which carries over to the mouldings. Draft angles for the parts must be considered if this option is required.

VDI Finish

A very controlled process which utilises an electrode produced from Copper, Graphite, or sometimes a mixture of both. The electrode is then fitted to an EDM (spark erosion) machine. This process can also apply a mottled controlled finish on the tool with a range of between VDI10 -VDI37 (draft dependent).  

Some Standard Finishes Available for Aluminium Tooling

PM-FO: Non-cosmetic – finish to Protomold discretion

PM-F1: Low-cosmetic – most toolmarks removed

PM-T1: Protomold texture, SPI-C1 followed by light bead blast

PM-T2: Protomold texture, SPI-C1 followed by medium bead blast


Aluminium Tool With Complex Contours



SPI Finish A-1 – Grade #3, 6000 Grit Diamond Buff

SPI Finish A-2 – Grade #6, 3000 Grit Diamond Buff

SPI Finish A-3 – Grade #15, 1200 Grit Diamond Buff


SPI Finish B-1 – 600 Grit Paper

SPI Finish B-2 – 400 Grit Paper

SPI Finish B-3 – 320 Grit Paper


SPI Finish C-1 – 600 Grit Stone

SPI Finish C-2 – 400 Grit Stone

SPI Finish C3 – 320 Grit Stone


SPI Finish D-1 – 600 Stone Prior to Dry Blast Glass Bead #11

SPI Finish D-2 – 400 Stone Prior to Dry Blast #240 Oxide

SPI Finish D-3 – 320 Stone Prior to Dry Blast #24 Oxide

These are just a selection of some of the finish options that are available for aluminium tooling at RP Technologies. For more information, and a comprehensive discussion on options for finishes, please email, or call +44 (0)121 550 5868.

action image
We can put your plans into action today

Award-winning aluminium tooling, plastic injection moulding, CNC machining, and rapid prototyping. We specialise in fast turnarounds of high quality components.

Want to know more? Get a quote