DEPRAG presents lightweight Screwdriving Function Module for robots 28 May 2021

Entirely new possibilities have opened up for assembly through the use of lightweight robots. Applications of this kind require assembly tools of an equivalently light weight. DEPRAG SCHULZ GmbH u CO has developed an innovative lightweight Screwdriving Function Module (SFM), which fulfils all the specifications for integration with a lightweight robot.

The increasing diversity of products, smaller batch numbers, and shorter product lifecycles, all present new challenges for assembly. Automated processing steps are often uneconomical for small or medium sized companies as they involve high costs. However, with the development of lightweight robots over the last few years, hopes have been raised. Manual assembly tasks can now be technically supported at a reasonable cost, thus utilising previously inaccessible automation potentials.

Low investment costs enable the fast, economical implementation of applications. Robots with a low load capacity are significantly more affordable and the total size of the system or machine is substantially reduced when using smaller robots. The lightweight SFM has a low weight of just 1.5kg with a maximum torque of 4.2Nm. This already includes the mouthpiece and nosepiece ensuring reliable assembly of the screw. The use of lightweight materials is indispensable in attaining this low weight. Whether components are made of composite materials such as carbon, aluminium parts from a 3D printer, or light synthetic parts – each gram counts.

Additive production processes can even be used, for example, to cost-effectively manufacture the required screwdriver adaptor using aluminium, or the mouthpiece using hardened tool steel. Carbon fibre tubes or sheets are lightweight but can bear heavy loads. Integrated robot specific attachments are also an option. This consists of an aluminium body combined with a carbon fibre sheet – eliminating the need for an additional adaptor.

Even in the construction of the Screwdriving Function Module, fasteners made from aluminium and bonded components are used to reduce weight even further. With all these weight optimised elements, the DEPRAG lightweight SFM is highly suitable for robots with low load capacities and is also designed to withstand the highest loads.

If the function module is equipped with DEPRAG spindle screwdrivers, a wide range of possibilities is opened up with seamless processing data acquisition and the creation of up to 1,000 screwdriving programs. This clears the path for production, which takes all elements of reliable screwdriving assembly into consideration – even for safety related fasteners. In combination with a DEPRAG screw feeding system, this single source solution supplies a comprehensively tested screwdriving unit.

The lightweight SFM can be used in conjunction with any DEPRAG feeding system – they efficiently and accurately supply fasteners in the desired cycle time. Precisely timed supply is an essential element for the productivity and reliability of assembly processes. Integration is particularly simple and convenient. The range includes step feeders, sword feeders, vibratory spiral feeders, as well as screw presenters. Fasteners either with or without a head can be assembled using the lightweight SFM.

The SFM itself can also be equipped with optional additional features. A screw depth sensor, for example, can be used as a shut-off parameter for assembly to depth with adjustment screws. This results in greater processing reliability for the relevant production step.

Processing reliability is further increased by utilising the most appropriate tightening procedure. Direct screw assemblies often result in fluctuations, for example due to varying screw or hole geometries; the structure of the component material; altering surface qualities; spring loaded elements; or seating conditions. According to the application needs and changing framework conditions, the most ideal procedure for the application can be realised with the screwdriving system: Choose from torque controlled or angle controlled screw procedures, friction value procedures or Clamp Force Control to detect seating point and therefore improve constancy of the pre-load force.

The lightweight SFM also provides a universal, flexible concept in regards to Industry 4.0 and system communications. The smart tool is supported by the software solution DEPRAG Cockpit and is particularly suited for use in the networked, digital factory. The software collates all assembly-related production data and presents it in a structured, user-friendly format. All screwdriving tasks can be parameterised, visualised, documented, analysed and optimised.

Deputy Editor

Claire Aldridge Deputy Editor t: +44 (0) 1727 743 889


Having joined the magazine in 2012, Claire developed her knowledge of the industry through the numerous company visits, exhibitions and conferences she attended both in the UK and abroad.

Claire prides herself on keeping readers well informed and up to date with the latest industry news.