Individual grease dispensing

Optimal power transmission for brake systems

DOPAG has developed two special lubricant application systems for the SFS Group AG, a global leader  in mechanical fastening systems, precision formed components and assemblies. Finding the ideal solution involved not only complex testing in DOPAG’s Technical Center, but also the manufacturing of a special adapter.

Modern vehicles offer a vast array of assistance systems designed to improve driver experience, while increasing safety. Think for example park assist, lane keep assist, electronic stability control, traffic sign recognition, proximity sensing, etc. There is always room for new functions. However, this goes hand in hand with increasing requirements on the integration of these functions into the vehicle mechanics. Across the automotive industry a great deal of effort is being put into finding effective solutions and at the Swiss company SFS things are no different. SFS provides the industry, among other things, with a variety of mechan- ical assemblies and components, for example from the areas of airbag and ABS/ESP systems, sensors, seats, doors or interior fittings. Founded in 1928, the company is now an international group with more than 80 sales and production sites across the world.

The SFS product portfolio also includes ball screws and screw jacks for electric parking brakes. These generate brake pressure by converting rotational movement into linear movement. The production of ball screws requires two lubricant applications, since the component must be both greased and oiled at the same time. For both these applications, DOPAG has designed individual dispensing systems that meet all the requirements in terms of accuracy, repeatability and cycle time.

The ball screw drive is greased on a rotary table using a chamber metering valve. The benefit of this valve is that it allows for a clean and precise application of material in the smallest dots. Only a few seconds are available for the greasing process, so the cycle time is extremely short. Material is supplied via a tandem version of the P200 drum pump from the DOPAG lubriLine range. This ensures that material is available to the fully automated production line at all times and that drums can be changed without interruption to the production. A material pressure regulator is interposed, reducing the pressure of the conveyed material to the required working pressure. As a result, the material is being discharged evenly at all times.

Thorough testing in the technical center
To achieve a truly accurate and even oiling of SFS’ components, DOPAG engineers additionally devised a special adapter. Initially, test series were carried out in the technical center of the DOPAG Competence Center in Cham, Switzerland. These showed that the shot valve would not be suitable for the application and that another solution had to be found to ensure the material would be applied in a perfectly clean manner. The answer was developing an additional, special adapter for the needle metering valve (0.05-1ml). The adaptor was performing well during further tests and after consultation with SFS, it was redesigned and finalised. The material is supplied via a pressure tank filled by a bunghole pump from a 200l drum. A gear flow meter is used to monitor the flow rate. Based on the volumetric gear displacement system, the cell is capable of measuring the exact flow rate with a very high degree of accuracy. This is all the more important when it comes to the production of components for the automotive industry, where automated production processes need to comply with numerous strict requirements. Finally, the two metering systems were delivered to a system integrator, who incorporated them into the entire production line.

Project plan

Depending on the parameters of each case, a metering unit can take various forms. Within a few project steps, DOPAG team and the customer reach a plant concept that meets all the application requirements.

  1. Customer enquiry
  2. Enquiry is processed by DOPAG (application form, datasheets, sketch)
  3. Feasibility study, first layout design, possibly testing in the technical centre
  4. Budget quotation is made
  5. Customer reviews budget quotation
  6. Further testing in collaboration with customer
  7. Fixed quotation is made
  8. Customer places an order
  9. Project engineering / elaboration of detailed configuration
  10. Production
  11. Delivery and commissioning