Inserts for Plastics

Tappex® has acquired for over 60 years comprehensive knowledge of the application requirements of Threaded Inserts fastening across global Plastics Industries. Our inserts have been designed for plastics installations in mind, have been extensively trialled and supplied for more than half a century to customers around the world, on land, sea, air & even in space.

Industries on a global basis specify several broad categories or groups of plastics and both our standard products and customer specials have been developed to meet the many different demands of these different plastics. The manner in which they are used dependant upon customer application(s).

In overview, groups of Industry plastics include:

• Thermoplastics - rigid at room temperatures but soften at elevated temperatures, ultimately melting if of Amorphous structure i.e. ABS, Nylon (depends on grade), PVC & Polycarbonate OR if of a Semi-crystalline structure whilst these do not behave in the same way, they do have a well-defined melting range i.e. PE, PP & PEEK are good examples
• Thermosets - once formed through molding, for example, they chemically change such that they cannot be physically re-formed /re-shaped, but are characteristically quite robust and stable at elevated temperatures i.e. Automotive 'under hood'  installations
• Foams – limited suitability for threaded inserts unless the holes are suitably cored. Tappex can offer a product for certain applications after further consultation and/or testing, where appropriate
• Elastomers – rarely suitable for threaded inserts although Tappex always prepared to give some technical consultation
• Composites - and growing in progressive usage, composite materials which may incorporate combinations of plastics, wood based fibres and/or light alloys can be supported by Tappex, after consultation, either with a Thread insert or bespoke fixing solution

Tappex® has a broad range of inserts for plastics to suit mold-in and post-mold installation dependant customer’s application requirements as well as in-house manufacturing process considerations. Our products suitable for inserts for plastics are as follows and include threaded inserts, in both female & male geometries manufactured in house in both Brasses, Steel & Stainless Steel ( 303 & 316 grades ) to suit application requirements:

In-Mold installation - HiMould®

• Brass inserts, normally female geometry, designed for maximum performance created by the external diamond knurl form combined with undercuts in both open and blind-ended versions
• After molding-in, usually being held in situ/place by plain not threaded pins for ease of the operator, without compromising a flash-free result
• a large number of shear points are created over the whole length of the insert which, in turn gives better axial and radial performance than other mold-in inserts in relation to it’s diameter
• Proven effective also in rotational moldings where the fill is not pressurized
• Brass inserts are much softer than the mold-tool steel so, should the insert be incorrectly installed, then there is a significantly reduced chance that damage would occur to the mold

• HiMould are available in variety of sizes from Metric M3 to M12, Unified with BSP and/or modified standard geometries possible including blind, counterbored & male versions

• Tappex are also developing for molding-in, higher strength (8.8 grade), steel cold forged male inserts called SplayMould® to meet more critical OEM / Automotive applications now

Post-Mold installation

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  Multiserts® - Press in

  • Multi purpose thread insert, normally made from Brass, pressed-in and for a wide variety of applications and operating environments
  • Multiserts include four primary designs: Unheaded, Single Thickness head, Double Thickness and Microbarb with different standard lengths (variants possible)
  • Suitable for different installation methods including COLD/HEAT/ Ultrasonics which, in turn, will influence installed performance
  • External barb or knurl form gives good flow characteristics, pull-out performance as does the headed versions in terms of inhibiting jack out if mating components are suitably designed
  • Plain top ring on headed versions gives bearing surface for mating components as well as inhibits movement of plastic , upwards, during installation

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   Microbarb® - Press in

• incorporates all the standard features of the Brass Multisert® range but with especially good pull out performance in thin material sections
• Microbarb® may be found most suitable also for vacuum formed, rotational moldings and fabricated constructions
• Multiserts/Microbarb® are available in variety of sizes from Metric M3 to M12 (M6 Microbarb max) with Unified threads and/or modified standard geometries possible, including male & steel versions

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  SETSERT/SURESERT/DEDSERTS® - Press in Thread Inserts

  • a range of Brass threaded inserts for more critical applications, but available now made from Steel & Aluminium materials
  • developed for installation into harder / filled thermoplastics (COLD) & thermosets; notch sensitive thermoplastics (HEAT) and also HEAT or Ultrasonically installed into suitable thermoplastics
  • Available in sizes metric M3 to M6, different lengths, single and double-ended versions and some with pilot lead in geometries (other sizes under development)

•  Triserts® - Screw in

  • Brass Self Tapping inserts (self-threading) with unique feature of enabling cold installation into most grades of Thermoplastic(s) and Thermoset plastics

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    Range includes three primary designs: Doubled ended, Reduced Headed and Regular Headed variants which will cover comprehensively a wide range of applications and operating environments
  • Triserts have three equidistant longitudinal cutting flutes, providing balanced cutting and reduced torque. A strong cylindrical-body is provided, when compared with cross slotted inserts, often an important consideration in critical applications
  • The design inherently also allows pull through applications, without any increased assembly torque problems
  • Trisert's offer, with suitable installation equipment (also available from Tappex), shorter cycle times and a good level of installed performance compared to competitor products
  • Suitable also for more critical plastics including hard urea, melamine and phenolic materials without cracking or molding damage
  • Available in sizes metric M2 to M10, with Unified and British Standard threads possible; steel and male versions also available

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  Foamserts® - Screw in

  • Self Tapping inserts, in Brass, similar to our Trisert®, but with a more coarse and elongated external thread form
  • Like Trisert, Foamserts have three equidistant longitudinal cutting flutes to provide balanced cutting and reduced installation torque. It is this combination that make it ideally suitable for structural foam materials, woods, laminated chipboards and medium density fibre boards
  • Range includes two primary designs: Doubled ended and Reduced Headed, the latter offers higher tightening torques and increased bearing area, whilst providing a flush fit where required
  • Available in sizes metric M2.5 to M8, with Unified and male geometries

• Compression Limiters (sometimes referred to 'anti creep spacers' )

  • Tappex offer a range of non threaded machined component parts which will provide localized reinforcement to plastic materials , under physical loads and where , over a prolonged period of time and/or subject to elevated temperatures creep or deformation is at risk of occurring
  • The component design, after consultation, is carefully determined both in length, diameter, clearance bore or through hole size and external location features to ensure that the installed clamping loads are borne by the compression component and not the surrounding plastic materials. Without such a component, over time, clamping load can reduce and this could lead to the male component working loose under extremes of shock or vibration which may lead to catastrophic failure
  • These components maybe designed either for mold in or post mold installation to suit a customers particular manufacturing requirements

Tappex have both standard components as well as offering the capability to develop bespoke solutions, to suit, in-house. More product information is available @ www.tappex.co.uk or please contact Tappex Head office and ask to speak with an applications engineer. Tappex has in-house design, development and manufacturing capabilities; Tappex holds International Quality accreditations.