Every manufacturing operation has a guy. That one guy in the shop who seems to have a knack for creating some cobbled together apparatus for holding, clamping or stabilizing a critical part in the operation of a production machine. In many ways he’s the blue-collar version of MacGyver and the guy you call when you need something held in place and shaped correctly to keep things going. But while the fix may be adequate, the use of such “cardboard engineering” methods may only last until the next changeover.
Chances are, this shop veteran is only applying to the production line the skills amassed during years in the machine shop fashioning workholding devices across an array of equipment. Workholding is a vital function in milling and machining and allows finished parts to be made in a repeatable and precise fashion. Whether used on a lathe or milling table, the workholding part must be able to withstand the impacts of machining, hold the piece in place without risk of movement and hold the piece in such a way as to not mar the part being produced.
Types of Workholding
There are many types of workholding used in modern machining. Some of the more common types include:
- Collets: Slotted and tapered sleeves that hold cylindrical workpieces on either the inside or outside diameter.
- Arbors: A device that grips the inside diameter of a piece to allow cutting or milling to take place on the outside.
- Fixtures: A device that holds the workpiece securely in place during the operation of a machine.
- Mandrels: A cylindrical and often tapered shaft that holds the inside diameter of a workpiece.
Often, a workpiece requires a shape, orientation or feature that isn’t simply squared or rounded. In these situations, the required workholding part used is a soft jaw. Soft jaws create an inverse shape of the part to be formed. The workholder then meshes with the part stock to hold it in place while milling is conducted to remove material. These workholding parts may require jaws or teeth, irregular shapes, oddly placed voids or unusual geometries to allow the part stock to be held correctly for milling or formation. These custom requirements add cost in the form of added labor and down time as well as in complexity that increases the chances of part failure. And by using the same equipment for creating the workholding part as is needed for finished parts, equipment utilization is affected as well.
Value Vs Cost
Workholding devices have traditionally been considered a necessary but non-value-added aspect of part formation. As complexity of the required workholding piece increases, no value is added to the final part and cost in the form of skilled labor over a longer lead time increases. Workholding pieces such as soft jaws, with their irregular shapes and features, also create more waste as more material must be cleared or removed to create the desired workholding piece.
Material considerations also impact cost. Workholding pieces must not allow the marring of produced parts. And most require that the piece allow no movement or slippage during milling. The use of specialized materials such as metal or ultra-high molecular weight polyethylene (UHMW) provide the slight give needed to prevent marring against the hard part stock while still allowing firm grip and no slippage. These soft jaw materials of choice are also expensive and when combined with the labor cost required to produce the irregular features.
3D Printed Workholding
3D printing offers many benefits over traditional formation of workholding pieces. And as material strength has improved within 3D printing it has become more viable as a workholding solution for many applications. Depending on required strength and impact requirements, materials with embedded carbon fibers or other reinforced material can allow for the creation of workholding pieces that reduce time, reduce waste and allow for more efficient use of production run milling equipment utilization.
When applicable, using 3D printed workholding has many key advantages.
- Non-Value-Added Transfer – Using 3D printing has a distinct advantage over traditional methods in that it transfers the creation of a workholding piece to a work center – the 3D printer – that functions as a cost reduction center. The piece is printed with no labor and without need of an operator. This allows the milling equipment that would have been needed for production of the workholder piece to be free to produce only value-added end use parts.
- Fewer Iterations Prior to Production – Often, a machine shop tasked with creating a new part may not have a sample of the actual part required. In these cases, experimentation using traditional workholding formation is expensive as many iterations may be required. With the CAD based functionality of 3D printing, the representation of the part can be created from an existing CAD file or be developed with CAD using part drawings. This allows inversions of the part for the formulation of soft jaws to be created with only one iteration, reducing the cost of experimentation and reducing the time for production. Time to quote, production time and waste are also improved.
- Improvements to Workhandling – Workhandling, like workholding, is vital in modern manufacturing, especially within highly automated production environments. With its potential to explore complex geometries and combine parts that traditionally needed assembly or joining, 3D printing offers the capability to create workholding pieces such as jigs and fixtures that can improve shop floor efficiencies. The same concept can be used with 3D printed end effectors to allow more efficient transfer of parts in a line. The piece not only serves as a workholding piece but allows control engineers and process engineers to consider not just the proper holding of work to complete the task but also how that work is held. In doing so, it is possible to combine workholding parts to eliminate whole assembly steps, improve safety and speed production.
- Agile Workholding – An outgrowth of lean manufacturing, agile manufacturing focusses on speed and in having the ability to quickly respond to customer and market needs while maintaining quality and controlling costs. With traditional workholding formation, the very equipment needed to produce end use parts was also required to produce the workholding piece. In cases where functional characteristics of the workholding piece may be less demanding with lower force of impact or movement, this may result in overengineered workholding solutions. With 3D printing, material development has advanced to provide durable, functional parts for workholding solutions for parts where machine impact or sheer potential is lower. This again frees CNC equipment and other milling equipment for dedication to end use parts and brings the concept and accrued savings and efficiencies of “agile” to workholding. The “right-sized” solution means less utilization of critical equipment for the non-value-added aspect of workholding.
Many traditional production operations are beginning to explore and use the options available with 3D printing for their organization. So much attention had been focused on 3D printing of finished products in the past that many were previously slow to realize its supportive aspects. But as the industry matures and improvements continue to be made in both equipment capabilities and in providing engineering quality materials, many companies are discovering its value as an ancillary tool that can reduce cost, waste and lead time and make their operations more agile. With the use of 3D printed workholding, that value continues to grow.
IC3D has over fifteen years of combined experience to help you develop the enterprise solution needed to develop and deploy effective workholding solutions to your shop. Our expertise can also help you determine tooling and materials for your R&D and production needs that will reduce cost and time to market for new products. Our staff can also assist you in creating or adapting improved designs for existing equipment that allows you to realize additional benefits not possible with traditional manufacturing. From our in-house base of large format printers developed by IC3D and specifically designed to reduce costs IC3D is a 3D printing service bureau, consumables supplier and partner in your project from concept to prototyping to completion. Please submit your project on our RFQ page.
Check out our line of materials online, or, if you’re looking for consulting, enterprise solutions or design needs, contact us and our staff will be happy to help guide you to the solutions you need.