Understanding Tooling Components Designing workholding systems for dependable production requires finesse and a deep understanding of all types of tooling components and their applications. A wide array of industrial supplies made from nearly every type of material is available to fit even the most unique design considerations.
The purpose of a workholding system is providing an accurate and reproducible process.
Whether a lathe, precision drilling, or molding, workholding systems guide machinery and hold materials steady for design specifications with extremely strict tolerances.
A stable system operates at high speeds without sacrificing accuracy or creating waste.
Drilling processes cut holes in metal for nearly every type of general manufacturing.
Turning processes cut cylindrical shapes from materials and is used in the finishing of bars and rods after they have been drawn.
Milling shapes materials for use in applications that require nonsymmetrical designs.
Considering Precision Machining
Some design elements to consider include the physical characteristics of the workpiece materials, their orientation, the external force of working machinery compared to the strength of the workpiece, and the machining platform itself. High-powered machinery and large loads can neither deform the workpiece nor any tooling components .
Every process has to conform to a high degree of accuracy, which requires locators and secure workholding.
The required daily output must be maintained while still achieving the highest amount of worker safety as possible.
Applying a high holding force with stainless steel clamps on a soft aluminum workpiece will result in deformed products that will never meet specifications.
Aluminum offers a good amount of strength while being relatively lightweight. This makes it an ideal candidate for the aerospace industry.
However, aluminum can be marred as it is soft. When tooling aluminum, special care has to be taken to prevent unwanted deformation of the workpiece.
Case hardened steel bushings and liners are often required.
Delrin is a plastic that acts as a metal substitute due to its wear resistance coupled with low weight and low friction when machined on a lathe.
Delrin can be injection molded for high performance engineering or milled for use in the consumer electronics industry. The FDA has also approved Delrin use in the food industry as well as for pharmaceuticals.
Light clamping forces are required when machining Delrin, but a molded Delrin ball or cone can be used as workholding for soft materials.
Nylon and phenolic plastics are soft, but relatively brittle. Phenolic plastics are used in spring plunger heads for workholding and nylon is used for self-locking threaded components.
Offering high strength and good corrosion resistance, especially with case hardening, stainless steel is a durable material well suited for tooling.
Many tooling components that require good impact resistance are stainless, from locators and liners to springs and plunger bodies in industries from construction to design and general manufacturing.
When an application requires a strong material that will not deform, bend, or even expand when heated, tungsten carbide is the best choice.
Tungsten carbide is ideal for low tolerance industries like aerospace and aviation.
Jigs And Locators
Setting a point of reference for a machining process is a vital first step to ensuring a precise operation. All measurements are taken from points of reference set with devices called locators or jigs.
The workpiece must be set correctly in its start position and all machine movements have to conform to that point.
After machining begins, jigs act as guides and machine stops.
A tooling ball is a single construction locator made of tungsten carbide that consists of a ball attached to a shank. Other locators are similar components that come to a point or ball for clamping into a point.
Types Of Jigs And Locators
Locators can be as simple as pins and holes. Simply align two holes, one on a machine and one on the workpiece and then secure the setup with a pin.
Other jigs might be a magnetic piece for setting locations on ferrous metals.
Some ball positioners come with a swivel action for angular positions.
Adjustable positioners consist of a pin on a slider that can quickly set multiple starting locations.
Even a set of clamps could be used in a pinch if the operation doesn’t require accuracy or will undergo a second set to refine a cut.
Fixtures hold a workpiece in place. Otherwise known as workholding, a stable, reliable hold is vital in ensuring high precision is met. The hold must be maintained and not be overcome by the vibration forces of the machine or its motors. Fixtures also offer a coupling for locators to connect to for lining up a production run.
Liners are the most simple fixture as they are the female part for tooling balls and shafts and are simply slots that can be attached to machinery.
Reverse mount bushings are used like liners, but can be installed from the underside of a table.
Ball lock shanks hold a ball with a locking mechanism.
Spring Loaded Workholding
Spring plungers, or spring loaded devices, work well, but springs are relatively fragile and can be difficult to install and use without a spring under tension slipping out of the machine.
Plunger heads can be fitted with plastics to offer a dent-free hold on even soft metals.
With jigs and fixtures, machines can operate with precision at a high rate of production.
To ensure such smooth operation, the design of workholding solutions is paramount.
When tooling components are made to a strict tolerance and use the appropriate material, the entire machining process is a marvel.