Heat Staking Procedures and Processes
Procedures, Process Parameters, and Guidelines for Plastics Assembling
The heat stake process is used in many high technology fields and consumer products manufacturing and offers many benefits.
Direct Contact Press Methods Using Precisely Heated Probes and Pressure
Thermal Press International, has developed a procedure that precisely controls heat and force in providing a high quality, clean, odorless, and safe upset heat stake procedure of modern thermoplastics. The heat stake process gives you repeatable performance without the high cost & noise of other types of processes.
Processes & Procedures for Staking
The direct contact method of staking applies force to heated metal probes, which contact posts then compress & form a stud head, For joining assemblies, metal to plastics, or joining two pieces of any another material. Excellent heatstaked results are possible when the post & material selection are initially configured for a heatstaking application. Precise heat & pressure can reform posts from a wide variety of thermoplastic materials. Some of the most common examples are abs, polypropylene, polycarbonate, abs polycarbonate blends, Polypropylene/polycarbonate blends & many other engineering materials (even with as much as 30% filler).
Very simple design guidelines are required for success. There are a number of factors that are essential in obtaining good heat stake results: post diameter, height, & geometry. Working height, (above the mating surface) should be approximately one & a half – two times the dia. This will result in a heat stake stud head dia. of approximately 1.5 – 3.0 times the post diameter. The selected material and its moldable thickness of the walls will determine typical diameters. For example, diameters can range from 0.04 – 0.09 inches.
Post Types – Flat Profile, Dome, Cross-Shaped, Rosette
Heat Staking posts & stud head geometry can vary as the application dictates. For through-hole fastening post: maintaining a flat-tipped probe tool for making a stud head into a flat profile is the easiest. Dome-shaped stud heads are aesthetically attractive plus provide a tight heat staked assembly (typically, tighter than the flat-tipped profile configuration), but require a dome-shaped relief be machined into the tip of the probe.
Cross-shaped post or hollow boss staking can be used where high retention assembly is required, but the design is limited because of the existing part constraints. The hollow & cross post designs allow the creation of large posts or thick rib sections of uniform thick wall thickness, while minimizing or eliminating sink marks on the A-side rib surfaces.
Rosette-shaped heat stake probes will flair out a hollow boss leaving the hole available for other operations (i.e. attaching additional components using self-tapping type hardware). A rosette-shaped flair stud head is aesthetically pleasing, plus has high pull strength characteristics (compared with other configurations previously mentioned), but requires more precision in the engineering and manufacturing of the probe.
Side swaging is used for post requiring the retention of glass lenses or other components. Side swaging can be successfully accomplished using angled contoured probes, used in forming the post or side – walls, capturing the component by its edge.
Clamping devices can be designed into the staking procedures ensuring proper contact & tightness of the assembled units. When joint clamping devices are used they can virtually eliminate joint gaps caused by warped parts, poorly fitting parts, & operator errors.
Efficient Dis-assembly and Reworking
Reworking a heat staked assembly is performed efficiently & consistently using heat staking. Dis-assembly is accomplished by piercing the stud head with a hot pointed-tip probe, re-flowing the stud head material: allowing a quick, clean removal of the stud head. A second set of posts for an additional heat staking operation or an alternate fastening system can be used in reassembling previously reworked parts.
Plastic Heat Staking is found in most industries and high technology fields that manufacture thermoplastic assemblies. Examples include: consumer electronics, automotive, telecommunications, medical device manufacturers, computer manufactures, PCMCIA cards, Memory Modules, Flash Cards, electronic badges, etc.
Using the direct contact press, heat stake method for assemblies is repeatable, economical and safe. The number of posts heat staked at one time is only limited by the configuration design of the parts being assembled.
Heat staking and sealing parts of all shapes and sizes provides an excellent means of plastic assembly. The benefits of being extremely quite, plus the versatility of doing a wide range of high tech post; from threaded inserts and other metal components, to micro miniature equipment assembly by providing cost effective means of adding or changing tooling make the process an excellent return on investment. In addition: the minimal wear characteristics of the tooling, low maintenance costs, high reliability of the equipment, and the added benefits of being safe for the environment provide for a long, trouble free, and clean operation.
We can help you today with your engineering, prototype development, and manufacturing needs. See how Thermal Press International can save you dollars on the bottom line while solving your most demanding assembly issues using our direct contact heat staking machines.
Contact Us at Thermal Press for more information.