How to shape a 150x150x10mm metal plate?

[mobefive]

Ok here is the breif,

I know very little about metals engineering so bear with me. What I am attempting to do is to create a small number of these plates (about 10 to begin with) that will be approximately 150x150x10mm and to be made out of some type of metal that is as light as possible and water(fresh)/weather resistant. It will be flat on the bottom and mounted to a waterski and be shaped on the top, hopefully smooth and shiny.

I was initally thinking aluminium that was embossed somehow to save on weight but then it must be a strong object as to not loose shape when knocked. Perhaps I can add some type of coating to get the requried shine and gloss at the end.

Let me know what you think, thanks in advance for any help you can provide.

Cameron Leake
mobefive@hotmail.com

 

[richardbuss]

Cheapest way would be to take a square bar 150 mm and cut the pieces off you need at the required thickness.

AISI 300 series stainless like 304/316 would be cheap stainless materials.PVD coating is used to provide optical effects in some cases.

Regards
Richard

 

[mobefive]

Ok that is what I thought I might have to do but I dont think I explained it very well. The piece, that I could easily cut off a bar needs to be shaped into a 3D logo and so I was thinking that it may need to be poured into a mould.

It would be great if you could tell me which metals would be suitable and how to create the mould. Ahh and I dont have access to too much specialised machinery.

Thanks,
Cameron

 

[ijzer]

You could try Aluminum cast by lost wax method.

 

[kenvlach]

I disagree with some of the above procedures.

First, you do not want indentations which will hold water and lead to corrosion. Use colors on a flat surface. This allows using thin material, which is less apt to be bumped and more conformable if the ski flexes.

To create your plates, the cheapest and easiest method is to buy 150 mm wide, bright finished strip, maybe 2 mm thick. Do any desired finishing of the edges and buffing, then cut (shear) the pieces in a brake press. Snip snip snip -- faster and less burring than saw cutting.

As for material, 316 SS is better than Al alloys or 304 SS for corrosion resistance. However, your options for coloring SS are limited: Paint, decals, laser engraving. Be sure to have the SS passivated before any of these steps.

Fishing reel manufacturers use polished and anodized Al-6061-T6 for a combination of strength, brightness and corrosion resistance:

http://www.flyfishinggear.info/fly_fishing_gear/fly_reels_other.shtm

For your application, I suggest a lower strength Al alloy of better brightness and corrosion resistance. Some which are available in strip/sheet are Al 1100, 1175, 5005, 5052, 5252, 5457, 5657, 6063 and 6463. For a very brief guide to anodizing, see

http://www.anodizing.org/reference_guide.html

Anodized Al is available in many colors. For fade resistance, use Black HBL for the logo, and either clear (non-dyed) or Gold 4N (aka FAO) for the background. To do the two colors, first have a batch of logos made up to serve as masking during the first dyeing. Use self-adhesive vinyl, rated to 100[sup]o[/sup]C and peelable w/o residue. Most suppliers, e.g., Shercon

http://www.shercon.com/home/

will precut to your design on backing paper.
Anodize pretreatment: Soak clean and deoxidize; do not caustic etch. Sulfuric acid anodize to 10-20 microns thickness (less is brighter, thicker is more corrosion resistant). Rinse, blow dry with clean, oil-free air, apply logo mask, dye in the background dye, seal, remove mask, solvent wipe to ensure masked area is residue free, then black dye (the previously sealed dye should be unaffected) and seal.

Attachment to ski: No holes or screws (corrosion source). Use a water-resistant adhesive; the logical choice being the same resin as the gel coat used on the skis. First, lightly sand the attachment area. Suggest also overcoating the nameplate with the same clear resin for corrosion resistance.

Hope this helps,
Ken

 

[mobefive]

Thanks Ken,

I will use 2mm SS Alloy of one of the types you have suggested then. I will cut what I can in a brake press, although with 2mm thick metal would it not be easier to use just a coping saw or a drill press/coping saw for holes then file the metal back?? I would then have to sand it back quite signifiactly to get rid of scratching however, perhaps not such a great idea.

The finish I desire would be either completely chromed(shiny) finish or a mixture of chrome and black. Will look into what you have told me.

Regards,

Cameron Leake

 

[mobefive]

I have found a picture of pretty much exactly what I want to create.

http://www.burton.com/Burton/gear/products.asp?productID=110

Any Ideas.

Cameron

http://www.mobefive.tk

 

[kenvlach]

Hi Cameron,
The Aluminum logo mats were probably closed die forged in a hydraulic press (with male & female dies, like coinmaking). Not economical for small quantities. The parts were not polished (a polished surface accentuate scratches in use), and I consider it likely that they are clear anodized. For smaller quantities, give a CAD drawing to a CNC machine shop.

What do they mean by 'mat?' Are these stepped on by people in boots? Would require thicker material, with the backside cavity filled with a rigid foam.

If you use flat shiny SS strip, I suggest 1 mm thickness. The 2 mm is more appropriate for Al anodizing. In either case, I suggest a 45[sup]o[/sup] bevel along the upper edges (but not the bottom edges; don't want crevices).
Ken