Hard surfacing anyone? What tolerances are normal?

[Cordon]

Hello all,

Just wondering if anyone out there does any hard surfacing, don't run into many company's that do. If so what kind of tolerances are the norm for you?

Thanks!

[Wes Bucey]

Welcome to the Cove, Cordon!

I'm aware of the processes commonly called "hard surfacing" which usually add either beads or a layer of hard, abrasion resistant material to a different material (which may be softer, but also "tougher" in tensile strength), giving a finished product with some of the attributes of both materials. The bonding of the two materials is usually heat based (gas or electric arc welding.)

In concept, this is very similar to "hard chrome" electrolytic plating and "plasma coating" of tool bits.

So, my question is, what is the application? Typically, design tolerances depend on the tool to which the hard material is applied. I'd expect a tighter tolerance on an impeller blade in a pump than on an open pit mine dragline bucket.

[Cordon]

Hi Wes,

We make traction and control products for snowmobiles. The hard surface is applied to the skags for extended life of the parts. The skags which also have brazed in carbide go on the ski's of the snowmobile to enhance handling.

[Wes Bucey]

Originally Posted by Cordon

Hi Wes,

We make traction and control products for snowmobiles. The hard surface is applied to the skags for extended life of the parts. The skags which also have brazed in carbide go on the ski's of the snowmobile to enhance handling.

I'm more familiar with boating than snowmobiles. I presume "skag" is a variant of "skeg" (strip attached to a keel for protection or sticking out from bottom of "stinkpot" to protect the propellor.)

Seems to me the tolerance you list will be a compromise between the design optimum and the cost of control. Very tight tolerances can be held when adding carbide to tool working surfaces (for lathes and mills.) The tolerances for carbide on the teeth of dragline bucket are a lot looser. Technically, you could hold the same tolerances for both, but why?