Modular Work-holding Design
Modular Workholding Design

The effort to design workholding is just as important as the design of the manufactured part. As machine shops become more automated and intelligent, workholding must advance in design efficiency as well. Workholding is now often required for small-to-medium-sized production runs and demands accuracy, versatility, and repeatability for a variety of similar operations. The investment of hundreds of thousands of dollars on automated CNC machines for a shop does not want to see them sit idle for any longer than is necessary. Modular workholding design is allowing faster transitions and use on multiple machines with smart pre-made kits containing an assortment of clamps, risers, studs, blocks, and rails.

A New Approach

The basics of workholding design (tag blog Choosing Workholding…) are to keep the tool in cut and depending on the material, speed, tolerances, dimensions, and the cutting tool itself. Moving into hydraulics, for example, will not repair a manual fixture that isn’t performing well, to begin with.

As the trend towards smaller lot sizes and higher accuracy parts continues, many manufacturers are finding that dedicated workholding systems end up on the shelf quickly never to be used again. Even in designing your own workholding consider the addition of pre-machined screw and dowel holes for quick mounting and attachment of preconfigured tooling blocks. Modular Workholding systems, available from a variety of manufacturers, allow multiple machining operations to be performed in one setup, often slashing both production time and cost. Adding clamping studs, retention knobs, or more advanced buttons or switches, eliminates the manual labour of loosening and tightening bolts for each production run.

Cost of Production

Modular systems generally have a high price tag, but considering run cost, scrap reduction, and machine downtime, they quickly provide payback depending on lot size.

The machine downtime, or setup cost. is the labour cost to retrieve a fixture, set it up on a machine, and return it to storage after use. Since dedicated fixturing and power workholding are faster to set up, they create lower costs than modular fixturing for larger projects.

The lot size is the average quantity manufactured each time the fixture is set up.

Initial Tooling cost is the total of labour and materials to design and build a fixture. Here, modular fixturing is cheapest because parts are reused, while the more complex power workholding systems initially cost more.

Total quantity over tooling lifetime is the lesser of the total anticipated production costs. Generally speaking, as quantities increase, the efficiency of power workholding yields the lowest cost per part.

Finding the right modular design for your shop can also lower production costs if the vises or chucks can be used on multiple machines, and multiple applications, such as hydraulic, pneumatic, and electric as you expand.

Read More
['Rapid Enterprises']
['Machine Shop', 'Cnc', 'Manufacturing']