Techniques in Industrial Fabrication

Learn about heat staking, a cost-effective method for joining plastic components in manufacturing, from the experts at AMS.

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In concept, plastic heat staking techniques refer to a plastic fastening process in which multiple separate pieces of material are compressed and retained to each other by deforming a protruding boss into a clamp-like stake, holding these pieces together.  This fastening method is often utilized when a more rigid, reliable bond is needed above friction fits and adhesive joints, but where higher-rated joints using threaded fasteners or plastic welding are not necessary.  

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Heat staking, which plays a large role in technical manufacturing industries, offers these benefits:

  • No consumable materials or additional fasteners (such as adhesives, threaded fasteners, inserts, rivets or welding fill rod) required
  • Low cycle time, high joining strength, multi-stake fastening with fewer production steps required
  • Nice aesthetic finish, leaving only fully rounded or flat stake heads visible
  • On average, lower quality control reject rates compared to adhesive bonding or welding, due to fewer variables in play with heat staking

Means and Methods in Thermoplastic Staking

We’ve described what makes heat staking techniques so beneficial, but how exactly does the heat staking process work? Heat staking utilizes a cylindrical plastic boss protruding from a base piece of material that extends through holes in separate pieces. This boss is then heated and forcefully pressed down over the top of the separate pieces, forming a rounded retaining cap or “stake” over the previously loose materials. The stake is then cooled using air or cooling fluid media, making the stake a permanent fastener.  

While the above steps may make it sound as if heat staking only comes in one single flavor, there are multiple variants of heat staking that target specific use-cases and applications. 

  • Various heating methods include infrared staking, hot air staking and direct contact heating (electrical) staking.
  • Multiple stake head profiles include round, flat, cone and even flush stakes.
  • Alternative processes and boss designs go beyond cylindrical boss staking, such as membrane staking, insert staking and even light-duty weld staking.
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Automating Industrial Heat Staking Fabrication

No matter the size, scale, speed or complexity required to manufacture products that include heat-staked joints, there are heat staking plastic joining systems available to handle the job. Automation plays a significant role in being able to heat stake at higher rates and duties, which we’ll describe next alongside traditional manual heat staking: 

Manual Heat Staking

For small, single-stake applications, manual heat staking is performed on a benchtop using a handheld staking gun or press. In these applications, operators must assemble, align, hold and stake parts by hand. This scale of heat staking is sufficient for low volumes and stake counts per piece, but can become cumbersome very quickly as staking rates and sizes increase. 

Semi-automated heat staking

This approach works for medium to high volume, moderate complexity projects where an operator can benefit from having some automatic support during the staking process. A semi-automated thermoplastic staking solution often utilizes a drawer-load staking compartment that operators load manually, and then actuated staking elements conduct the heating, staking and cooling process automatically.

Fully automated heat staking

Automation is best for the highest volumes and complexities, as well as where labor availability is significantly constrained. A fully automated heat staking machine can complete multiple heat stakes on parts as they progress through a continuous process. These machines can include multiple automatic positioning, assisted cooling, quality control, labeling and cleaning steps all inline.    

AMS offers two plastic joining system platforms that can provide heat staking along with other plastic fabrication processes.  Our PJ-301 and PJ-401 plastic fabrication systems are excellent options for semi-automated heat staking, as well as plastic forming, insertion and ultrasonic welding. 

Applications in Thermoplastic Staking

Heat staking is prevalent throughout multiple industries, holding products together across a wide range of personal, commercial and industrial applications including automotive parts, medical devices, electronics and consumer packaged goods. Personal electronic devices, plastic toys, mobile phones, tools, furniture upholstery and countless more products all rely on heat staking for their lightweight, small, secure bonds.  

Another way to view heat staking is through the lens of the materials most commonly used in stake joining. Heat staking is most often used with polypropylene, polycarbonate, ABS and nylon thermoplastics. Heat staking does not have polymer compatibility with thermoset plastics, as these plastics are structurally static and unchangeable after their initial molding.  

Heat Staking Techniques - Applications in Thermoplastic Staking

Staking a Claim in Thermoplastic Joining Solutions

Using tightly controlled heat and pressure applied onto small areas of otherwise larger components, heat staking techniques offer attractive paths toward resilient attachments at competitive per-unit costs.  

As production demands and scales grow, automated heat staking solutions offer even greater advantages to industrial manufacturers balancing costs, part complexities and customer demands. 

Could heat staking be the answer for your assemblies? Contact us today for a free application review. 

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