6 Criteria to Keep in Mind When Choosing Workholding Devices
When you need to firmly and precisely attach materials to a machine table, there are a number of ways to do it. There are factors to understand before looking for a workholding device. Here are six criteria to keep in mind when choosing workholding devices.
- Part Size.The most important factors of a good workholding device are stability and access. These have a direct connection to workholding, and having a balance between these two is important. The device may be large and can deliver rigid holding, but heightens the chance of access to the piece being limited, and vice versa. If a part is too small for your fixture, opt for palletizing different parts. If a part is too big, then consider upgrades of modular pieces, or adding custom pieces.
- Part Shape and Condition.Choosing the shape comes down to whether your part is round or prismatic. A vise will work fine with prismatic parts. For round parts, you will need an outer or inner diameter for the part like collet chucks, lathe chucks, or V-blocks.
- Number of Axes. Prismatic parts would need multiple machining axes, which requires a different set of workholding considerations. The workpiece needs to provide clearance for movements without creating interference areas that can crash the machine. This usually happens between the table and the spindle housing of the machine. This is caused by needing a wide angle of attack to the workpiece from the spindle to the table.
Elevating the workpiece with a riser chuck gives machining access and allows the use of shorter tooling, resulting in better cutting parameters, faster feed rates, and heavier cut depths. Form and positional tolerances are enhanced when different faces of a large workpiece are machined in only one setup. A quick-change workholding piece can be attached directly to the underside of pieces that require to be held without any side restrictions.
- Production and Mix Levels. Regularity and difficulty of part changeover will impact how fast you need your workholding to be. The higher the part mix and production level, the higher the number of changeovers. Think about how much time a workholding piece will need while locating and clamping.
- Level of Operator Interaction. Workholding focuses on the ability to clamp and unclamp the part repeatably and precisely with the help of air or hydraulics. There are three levels of automation for consideration:
- Fully Automatic – Loading and unloading of parts and fixtures are done automatically, including clamping of the systems
- Partially Manual / Automatic – This is a mix of manual loading and automatic clamping
- Fully Manual – Setup and clamping are done by a person
Automation chucks open and close with just a switch flip. An operator can identify a part that is ready for machining, or parts that are unlocked and ready to move without the need to make different touches.
- Options and Accessories. If a job has unique demands, you have to look beyond the core workholding system for options and add-ons. UNILOCK chuck design goes beyond standard sizes and shapes. They can sit on top of tables, and can be incorporated into plates, EDM machines, CMMs, or robots. The Turbo option can multiply clamping forces from several hundred pounds to thousands if needed.
Mitee-Bite clamps are geared towards improving productivity, and capacity, and providing solutions for difficult workholding applications. Workholding should never be a reflection. Never assume that what you have around the shop will get the job done.
You can order Mitee-Bite clamps from Suncoast Precision Tools. These are compact, low-profile edge clamps geared toward improving production solutions for difficult workholding applications. Check them out here.