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World-leading industrial fastener specialist EJOT has developed two products which in combination make it much easier for designers and engineers to optimise the strength and speed of automated fastenings into a range of light metals.

EJOT’s ALtracs® Plus screws are self-tapping fasteners designed to give high-strength joints in metals up to a hardness of 140 HB.

ALtra CALC prognosis software has been developed by EJOT to support designers at the pre-engineering modelling stage. It has been developed specifically to enable engineers to get maximum performance and cost benefits from using ALtracs® Plus screws in any high-capacity application. Its early use produces significant cumulative cost savings.

The rationale for ALtra CALC was that while ostensibly similar software tools existed, they were geared to the requirements of international engineering standard VDI (Verein Deutscher Ingenieure) 2230, which lacks detailed guidance about joints using self-tapping fasteners.

In particular, VDI 2230 says nothing about the process of thread-forming and about the specific properties of directly fastened light metals such as aluminium and magnesium.

As a fastener industry leader, EJOT felt that this omission needed addressing urgently – hence its in-house development of ALtra CALC, a powerful and precise design aid that can be easily integrated into CAD/CAM systems and has already proved its worth in many automated and semi-automated assembly operations.

ALtra CALC can be customised to meet specific requirements and is a robust platform for further developments. EJOT is happy to discuss how it can be used to best advantage in specific assembly environments using ALtracs® Plus screws, but the core characteristics of ALtra CALC are these:

Screw joint dimensioning

For standard dimensioning of joints using ALtracs® Plus screws, ALtra CALC® calculates the precise effect of different combinations of material dimensions and specifications. ALtra CALC models the effects of using different light metal alloys, thanks to its internal materials database. This both speeds up and eliminates uncertainty from the calculation process.

Clamp load design

Clamp load, the main ‘quality criterion’ of a screw joint, is the prime focus of ALtra CALC. Inputting the desired clamp load along with data about the mating and clamping material, ALtra CALC instantly determines the screw dimension and tightening torque needed to safely achieve the clamp load in a specific assembly process. Reverse calculation – determining the clamp load from a specified tightening torque – is also possible.

Simulation of coating and lubricating effects

When fastening directly into light metal, the nature of the screw surface or coating can significantly affect torques and clamp loads. ALtra CALC® is programmed with fourteen different screw surfaces, each of which can be optionally combined with various lubricants. Further variables are the fastened material and the head connecting surface. All relevant friction values are determined and used to calculate the torques and clamp loads.

Calculation of optimum assembly parameters

EJOT ALtra CALC can calculate potential screw failure modes, such as stripping and fracture, and the exact point when they might occur – for example, as clamp loads or pull-out loads are exceeded. This extremely valuable ALtra CALC function enables designers to optimise installation parameters for process-reliable assembly by effectively eliminating failure risk.

Advantages of ALtra CALC

Using EJOT ALtra CALC in conjunction with ALtracs® Plus screws delivers a powerful user advantage, particularly if ALtra CALC is used early in the design and specification process.

Feedback not just from EJOT’s R&D but also from many industry applications confirms a marked reduction in development time, which in turn leads to significant savings in component design and development costs.

ALtra CALC prevents over-dimensioning of the screw joint, leading to material and weight savings; and far less time (and cost) needs to be spent on component tests and assembly trials.

Try ALtra CALC ‘lite’ for free right now

ALtra CALC is available to EJOT customers online. Simply visit -follow the ‘CAD & more’ link and either login or register.

This gives free access to a ‘lite’ online version of ALtra CALC. It is designed for maximum user friendliness so that it can be tried out immediately and independently.

For more complex applications that may be beyond the scope of the ‘lite’ version, simply contact EJOT and ask for advice and support. As EJOT has been a global centre of excellence in assembly fastener technology for a century, there will be no better place to enquire!

Since 1922 the German owned EJOT Group has grown to become arguably the largest original manufacturer of fasteners and fastening solutions that span multiple sectors and individual markets including Automotive Engineering, Consumer Electronics and the Construction Industry.

Here in the UK the company’s philosophy of market proactivity is evidenced by its product range and its support to designers, manufacturers and OEMs. EJOT has gained widespread approval for application specific products, achieving technical compliance through comprehensive development procedures, gaining acceptance from engineers and procurement alike. Technical testing, development and support is provided by the EJOT Applitec Centre which is based within the company’s UK manufacturing centre in North Yorkshire, with additional expertise provided by sister laboratories around the world.

Advanced fastening solutions for engineering

EJOT’s product and service capability to industrial engineers is based on cost-reduction through intelligent purchase. The realtime cost of managing a fastener impacts in five critical areas; the fastener itself, assembly, quality of joint, procurement and logistics. EJOT’s ability to create either one-sided assembly or part-reduced solutions means its products consistently deliver significantly higher performance resulting in genuine ‘bottom line’ savings. This way, cost reduction does not equate to a lowering of quality.

EJOT’s traditional engineering product portfolio includes high quality fixings for thin sheet through to cast metals, alloys and thermoset plastics. The technology to ‘build lighter, build stronger’ has seen the company develop market leading solutions for fastening into lightweight materials such as EPP foams and honeycomb composites. Leading manufacturers from the automotive industry are now adapting EJOT’s licenced EJOWELD technology for joining high strength boron steel to lightweight aluminium.

EJOT provides sophisticated prognosis and forecasting software bespoke to the company and exclusively for customers to benefit by. Application Engineers assist with project development from concept to production line.

By reducing the inspection required and also the number of unnecessary parts needed, procurement and inventory management also becomes much easier. Pre-engineering, or tear-down analysis can be freely undertaken from the initial consultation. Project management is led by experienced application engineers who are supported by the Group’s unique and highly sophisticated development arm Applitec, with sister laboratories based in Germany and at the Group’s UK base near Leeds.

Applitec research and development centre

Ejot products are high in quality, always corresponding to current technical standards by investigation and development. The competitive market and changing demands require a fast response to maintain this quality and to meet Global standards — often before they are even issued. It is for this reason that EJOT developed its own unique Applitec facility in the UK. It’s here that testing for all aspects of fastener technology, from simple dimensional and three-dimensional analysis to testing the mechanical, structural and material dynamics of properties of the product and performance in application.

Globally EJOT operates 15 manufacturing centres in ten countries, employing over 3,100 people. In addition to the manufacturing operations the Group has 34 subsidiaries in 32 countries, with six research and testing centres in strategic locations. EJOT has also developed partnerships with several academic institutions, aimed at maintaining the development of advanced fastening solutions for the future.

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