CNC Grinders: Why Grind When You Can Hard Turn?

Most of you are familiar with the Okuma CNC Lathes and Machining Centers, but did you know that Okuma has a full line of cylindrical OD and ID CNC grinders?

CNC Grinders: Okuma’s Best Kept Secret

At IMTS, I posed this question to many of the attendees walking through our booth. Based on my “unofficial” survey, I found many people were not aware that Okuma offers CNC Grinders. I would then take them over to the GA-26T OD grinder we had on display and show them some of the features of the machine. During this discussion I was repeatedly asked the same question…”why would I grind when I can hard turn?”

While advancements in CNC machine tool technology and tooling have made drastic strides in favor of hard turning, we grinding guys can rest assured there will always be a need for CNC grinding.

7 Reasons to Grind Rather Than Hard Turn:

1. Surface finish, size and roundness requirements: A grinding process can achieve a 6Ra, hold less than a .0002” size tolerance and grind parts to within 30 millionths roundness.
2. Ceramic and Carbide material: It’s a more cost effective and stable process to grind ceramics and carbides than it is to turn them.
3. “No Lead” requirement: This is the “spiral” you see on a turned shaft. This can cause premature failure of seals on a shaft. By plunge grinding the shaft, the lead is eliminated.
4. The customer you supply parts to requires the part to be ground: Markets such as automotive, aerospace, and medical require parts to be ground rather than hard turned.
5. Interrupted cuts such as keyways or splines: Depending on the shape and size of the interrupted cut, this may cause premature chipping of the insert in hard turning. A grinding wheel is not affected by the interrupted cut.
6. Tooling cost per part: I’ve seen a grinding wheel last 120,000 parts before it needs to be changed. The wheel cost was $600 so that’s a half a penny a part!
7. Less down time: How many times will the insert need to be changed on the CNC lathe throughout 120,000 parts?

Do you have a particular application that may require CNC grinding or hard turning? Not sure what process would be the best? That’s where Okuma, our distributor network, and our Partners in THINC come in. With our expansive breadth of products and our depth of service and support, we have an endless amount of expertise in both grinding and hard turning. So comment below or contact us. We welcome the opportunity to work with you in developing the best process for your application.

Rob Titus is Applications Engineer - Grinder Products, Okuma America Corporation