Technical Report
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Automation retrofit increases productivity

Consistent application of automation in a production environment

While many major companies have moved their manual production processes to low-wage countries, medium-sized family-owned firms often have quite a different perspective. They tend to first look at all the options for increasing efficiency and productivity at home before they take such far-reaching measures. One of their options to increase efficiency is to automate all manual production processes.

However popular the outsourcing and relocating of manufacturing facilities overseas may be—the best opportunities for succeess in series and mass manufacturing in traditional industrialized countries comes from leveraging existing capital in the form of skills, expertise, as well as in the pragmatic application of automation. There are many examples of the successful application of this strategy in medium-sized companies that cannot, like larger companies, simply “pack up and leave.” The crucial advantages of the typical medium-sized company in the fabrication and manufacturing industries have always been their unique mix of highly motivated and experienced skilled workers, application of new technologies, flexible use of people and machinery, and pragmatic automation strategy.

A crucial competitive factor: The pragmatic use of automation

Meanwhile, more than 300 customers are using Zepf’s fabricating and finishing services, resulting in a range of approximately 3,000 different types of parts which must be machined. For circular grinding, the parts can range in diameter from 0.5 to 30 mm, with lengths of up to 300 mm. For deep hole drilling, diameters are between 2 and 20 mm, with depths of up to 500 mm—or 35 times the drilling diameter.

To complicate matters, most of the orders are for small batches ranging from a low of 10-20 parts to a maximum of 10,000 with additional single parts. This represents a major challenge, in terms of staffing, machine capacities and cost effectiveness. “We primarily add value through machining, and then through the quality of our services,” explains Jürgen Zepf, the founder’s son and Co-Managing Director. “But the strong pressure on cost efficiency in this highly competitive market does not allow labor-intensive operations, which is why we have to pull out all the stops when it comes to processes, efficiency and automation in order to be profitable. In SHL Automatisierungstechnik, we have found a creative and reliable partner for our manufacturing automation needs. With their help, we are making processes, such as grinding, more efficient, step by step.”

In cooperation with SHL Automatisierungstechnik AG’s application engineers, they created a proposal for an unconventional handling solution and then, after a thorough review, implemented it. The entire handling system is designed as a portal installed above the Agathon grinder—or its working area (Images 2 and 3). It consists of a H3L Motoman Industrial Robot (5 kg load capacity) with universal vacuum gripper, a station each to the left and right of the robot for placing pallets filled with parts, the controller with its software, and of course, the mechanical and electronic connections to the grinder. The pallets are designed and built to be multi-functional and can be adjusted for different parts diameters and lengths. Depending on the type and shape of parts, up to 160 parts will fit on a pallet or a total of 320 for the two pallet shuttle table system.

For centerless grinding, the machining cycle time is 10 seconds, resulting in a production cycle for the machine or cell of 3,200 seconds with zero man-hours. Automated part loading into the machine and unloading onto a deposit chute is performed, except for the actual parts change, in parallel with the cycle time, thus bringing unproductive ancillary times down to almost zero. This autonomous functionality allows skilled workers to operate multiple machines, thus eliminating unproductive ancillary times, as well as machine downtimes.

What is interesting here is that—despite the somewhat complex requirements—this part handling system was mostly implemented using the standard range of modular SHL automation components, and a standard industrial robot. Its total cost corresponds approximately to the annual cost of two unskilled workers. The centerless CNC grinder can, however, now run in 1-, 2-, or 3-shift operation, with the current manufacturing mode being 2 shifts.

Automation on demand

A great advantage in retrofitting automation is that existing and new machinery can be automated, thus reducing the initial investment outlay for a new machine. It should also be mentioned that in this example, a very space-saving, practical portal solution was created, which was completely assembled and tested at SHL and then installed on Zepf’s machine within a very short period of time.

Jürgen Zepf and his employees are very happy with their robotic solution. Zepf adds, “For us, the SHL robotic solution has resulted in more cost-effectiveness for several reasons. Due to the fact that one person can operate several machines, we have achieved a higher level of utilization, as well as a higher throughput per unit of time. In addition, order delivery times have been reduced.” According to Zepf, the machines keep running now during the breaks and into the shifts, relieving personnel bottlenecks. Robotic loading / unloading is precise and reproducible, and unintended grinding wheel contact has been eliminated, resulting in longer grinding wheel life and improved work-piece quality.

Summary and forecast

As Zepf sums it up, “Overall, this type of robotic automation is very worthwhile since in terms of monthly sales per month each additional hour a machine runs productively will result in a plus of about EUR 5,000. Consequently, we will continue to retrofit additional machines with SHL’s support. This will allow us to operate more machines with the same staffing levels, resulting in a corresponding increased throughput, and thus, more sales.”