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 https://www.ejot.com/Service-Industry_international -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!
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