As always, feel free to contact us for assistance with your application. Join our email list or follow our social channels for regular tech tips. Need assistance with your application? Contact one of our technology specialists to review your parameters. About Careers Loading Indexable Milling. Machine Vises. Hand Tools. This eliminates deflection and vibration commonly associated with ER collet chucks.
Now you have the perfect setup for hardened steels, you then need to consider how to use these; this will make or break your success. Chip load varies widely; if the load is too low or too high it will cause tools to either wear out too fast, chip or break. Lots of high speed and feed cuts with small cut depths is the best way to go to ensure a quality product. What tool holder am I using if ER collet chuck or side lock, you will need to rethink!
The store will not work correctly in the case when cookies are disabled. My Account. Currency GBP. July 16, Luke Jackson For many precision engineers, machining hard materials such as tool steel, D2 or H13 hardened steel seems like a difficult challenge. This means tools up to mm diameter can be used for milling hardened steels!
The 2 problems which ER chucks and side lock arbors are: Balance — Whilst they may be balanced to 15,RPM or greater in the factory, once assembled with a collet and tool this will not be the case. Shrink Fit Chucks Shrink fit chucks are excellent for hardened steel machining with perfect concentricity and a precise 3 microns run out making is easy to maintain balance at high cutting speeds. Hydraulic Chucks This is one of my favourites! Chip load equals feed rate divided by spindle speed multiplied by number of cutting flutes.
Some key questions you could also ask yourself to try resolve issues include: 1. Am I using a tool suitable for high hardened steel?
Am I cutting wet or dry 3. Am I running it fast enough go too slow and the tool will wear quicker 5. About author Luke Jackson. Recent Posts. What are the best inserts for turning hardened steel? We suggest starting at the low end of the recommended sfm and work up to the optimum speed. Table I below gives some representative parameters proven for hard turning.
As these figures show, the essence of hard turning is high sfm and low depth of cut. The first question a shop needs to address regarding hard turning focuses on the machine tool. The issue, summarizes Mr. McCarthy, is rigidity. Hard turning requires a rigid machine with a rigid toolholder system. Otherwise, the cutting tools will wear quickly and be prone to chipping.
Surface finishes will be poor and dimensional accuracy will be questionable. CNC lathes are recommended for hard turning, but manual lathes can be effectively utilized as well. A manual lathe must be in excellent condition and have very little play in the cross-slide toolpost and tailstock.
McCarthy notes that shop managers should be careful not to assume that older equipment will be inadequate or that newer equipment will automatically measure up. In an occasional instance, a shop that has been under pressure to get a good return on the investment represented by a high-ticket turning center may find that heavy use has produced more wear than might be expected, whereas a well-maintained manual lathe subjected to less demanding duty may actually turn out to be a candidate for hard turning.
The lesson here, Mr. McCarthy stresses, is that the best piece of equipment for taking advantage of the hard turning process is an open mind. As a general rule, if the lathe generates vibration, chatter, and poor surface finishes with carbide tools, it would not be a good candidate for hard turning.
Regarding toolholders, Mr. McCarthy has this advice: Standard toolholders work fine to clamp the insert for single-point cutting. The toolholder clamping components, however, must be in good condition. Carefully examine the top clamps, cam lock pins, and screws. If they are worn, replace them. Ditto for the chuck or fixture that will hold the workpiece for hard turning. Be sure it is in good condition. Check jaws for wear. A solid grip on the workpiece is essential because "vibration is a CBN tool's worst enemy," as Mr.
McCarthy reiterates. The point is, in most cases, where toolholders and chucks are in good repair and are properly used, they can also be used for hard turning. Hard turning does call for a change in thinking about the shape and style of inserts that are applicable but not a radical shift in tooling concepts. That common sense is a principle guiding factor becomes clear in some general guidelines about hard-turning Mr. McCarthy offers. For example, in most applications, hard-turning inserts should be negative geometries.
Negative rake angles give good support to the cutting edge, where it is needed most because higher speeds and relatively light depths of cut concentrate forces there. However, in certain boring operations, positive geometries are best because they are available in different inscribed-circle sizes, such as 0.
Likewise, to protect the cutting edge from chipping, a T-land or K-land is a must on hard-turning inserts. An edge hone also helps the edge resist chipping. Standard K-lands appropriate for hard turning are from 10 to 25 degrees by 0. McCarthy points out another oddity about hard turning with CBN that sometimes defies expectations.
Generally, the grades used for hard turning inserts are those having roughly 50 percent CBN content, depending on the manufacturer. Grades with a higher content of CBN, on the other hand, are used for conventional turning of softer materials such as powdered metal, gray irons, and certain super alloys. McCarthy stresses that shops should not be afraid to experiment once they get a feel for hard turning.
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