Tag Archives: repeatable chuck

  • 5 Technical Advantages of SMW Autoblok Quick Jaw Change Chucks

    Screen Shot 2017-02-20 at 10.17.49 AMWhen an expensive CNC machine is down for setup, productivity drops, along with a shop’s bottom line. For this reason, Quick Jaw Change (QJC) chucks were developed by SMW Autoblok engineers. The main reason for the new design was to reduce down time during job changeovers. It was soon discovered that the technology provided many other benefits as well.

    With standard chucks, the operator typically bores a set of jaws right onto the master jaw. Removing the jaws requires the removal of six bolts (which can be lost or dropped into the chip pan). With QJC chucks, the master jaw, top jaw and bolts are a sub-assembly that can all be simply removed together with a t-handle wrench on the side of the chuck. It’s faster, but that is only the beginning. In this article, we review the top five technical advantages QJC chucks provide in the shop.

    The QJC removal procedure alone allows for faster changeover of the jaws and speeds up production. However, jaws on standard chucks are also made of softer steel than QJC chucks. To maintain tolerances, they have to be re-machined every time they are removed from the machine.

    Just in Time (JIT) parts ordering forces manufacturers to run small batch sizes. More changeovers mean more time for set up and re-machining the tooling. Depending on the expertise of the operator, this could take up to 15 minutes for a smaller chuck. If you change four times a shift, that’s an hour lost from production time. Made of harder steel, QJC chucks have far superior repeatability. Since they don’t have to be re-machined, changeover time is reduced down to one to two minutes (only 4-8 minutes per shift).

    The accuracy of a brand new standard chuck might be adequate, but as the soft body starts to wear, the metal starts burnishing and removing itself and the workpiece quality suffers. The hardened steel of the QJC chuck changes the picture dramatically. A 260mm chuck is repeatable within 26 microns. To put that into perspective, a human hair is 75 microns thick. Quick jaw change chucks can maintain these tolerances for over a decade.

    The steel body of a standard chuck is so soft it can easily be marked with a file. When the master jaw and the chuck body of a standard chuck are actuated, they rub together. If not greased properly, the surfaces end up wearing. This wear can be increased by over clamping. Standard chucks can last up to three years if well maintained, while the hardened body and master jaw of the QJC chucks allow them to stay in service for ten years or longer.

    Reduced Hysteresis
    When chucks run at high RPMs in a CNC lathe, centrifugal force actually causes them to grow. This is called, “hysteresis.” You can’t see it with the naked eye, but the mass of a soft-bodied chuck microscopically enlarges enough to actually clamp the part harder at the end of the job than at the beginning. Thin-walled parts can be deformed due to the additional clamping force. Customers can run delicate parts at higher RPMs with the QJC because the design resists hysteresis and maintains its shape.

    Some parts companies have higher margins (and do better business) with replacement chucks than they do with the initial sale. They sell in bulk to machine tool companies for installation on standard units. Margins are so low, the vendors are basically betting that they will reap the benefits when the jaws have to be replaced. With all the advantages outlined above, the QJC provides much better value for just a little more investment up front.

    With over 25 chucks in our SMW Autoblok lineup with the Quick Jaw Change feature, there is sure to be a solution that meets your needs. Contact us to find that solution today.

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