Mechanical and plant engineering

Fischer: 101 injection presses and 9 million plastic plugs a day

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It’s hard to find a company that embodies the German spirit of innovation better than Fischerwerke GmbH & Co. KG. Founded 62 years ago, it is now one of the world leaders in fastener technology.

For 30 years, Professor E.h. Senator mult. E.h. Dipl.-Ing. (FH) Klaus Fischer has been at the helm of the company group. Under his leadership, Fischer has developed into an internationally active enterprise offering reliable, cost-effective solutions in the chemical, steel and plastic sectors. The foundation for this was laid in 1958 by company founder Artur Fischer with the invention of the “S plug”, an expanding plug made from plastic. With more than 1,100 registered inventions and 570 granted intellectual property rights in Germany alone, he is one of the country’s most influential innovators. His most important inventions include the synchroflash (1949), undercut anchors for concrete and fischertechnik construction kits. Nowadays innovation is on every employee’s agenda at Fischer, and it is not limited to products. Each year the staff generate 14 patent applications for every 1,000 employees.

This innovative force can presently be seen in Waldachtal in the Northern Black Forest region, where approximately nine million plastic plugs in all imaginable varieties are produced every day. In order to manufacture these enormous product volumes, the company currently has 101 injection presses available. The majority of these precision machines were made by Arburg. Injection presses from Ferromatik Milacron and Netstal are also used. The injection presses operate 24 hours a day. Around 11 metric tons of plastic granulate are processed each day for the daily output of 9 million plastic plugs. Fischer relies on absolute top performance. Everything must work perfectly. The central maintenance department, with a staff of 12 led by Werner Stahl, is responsible for the maintenance of the equipment in the Waldachtal plant. Their duties also include filling, monitoring and servicing the hydraulic systems of the equipment. An injection press holds 200 to 700 litres of hydraulic fluid, depending on the model. HLP 46 hydraulic fluids meeting the DIN 51524 T2 standard are used. Quality is a key consideration in the selection of the hydraulic fluid. Fischer’s maintenance technicians impose precisely defined requirements on the hydraulic medium, such as:

  • maintaining a high purity class, starting with the delivered fresh fluid;
  • good filtration characteristics;
  • rapid air separation capability, since excessive dissolved air in the fluid can cause cavitation in pumps and valves;
  • zinc-free and low-ash for the latest generation of machines;
  • high aging stability;
  • reliable corrosion protection.

    Maintaining optimal purity classes is a particularly crucial criterion for fluid selection and assessing use characteristics. To avoid the impairment of components or oil lifetime by residual contamination, even fluids prefiltered by the manufacturer are always filtered again before they are added to the hydraulic system. Although the injection presses are equipped with microfilters as standard equipment, the hydraulic fluid is also filtered again once each year with a mobile bypass filter unit as part of preventive fluid maintenance.

    The aim of the maintenance staff is to achieve the longest possible oil lifetimes together with maximum operational reliability of the equipment. Consequently, the hydraulic system contents are changed solely on the basis of the condition of the fluid, rather than on the basis of the number of operating hours. Here OELCHECK lubricant analyses serve as trustworthy control and monitoring tools. At least once a year, fluid specimens are taken from the hydraulic systems of all injection presses and tested in accordance with Analysis Set 2.

    Fischer’s maintenance staff have already managed to achieve considerable savings with the consistent implementation of their strategy. After all, the time required to take specimens and the price of an oil analysis are negligible compared with the effort of an oil change or the cost of a new charge of hydraulic fluid. What’s more, Fischer has sworn to banish every form of waste in its operational activities. There’s a good reason why Klaus Fischer was once called “Germany’s greatest process optimiser” in a major newspaper.

    Analysis Set 2: ideal for stationary hydraulic systems

    • Precise determination of particle counts and sizes with indication of the three purity classes according to ISO 4406, as well as other particle sizes greater than 21, 38 and 70 µm in accordance with SAE 4059.
    • Wear metals. Copper, which is present in pipes and non-ferrous alloys, is especially significant. In addition, trace amounts of iron, chromium, tin, lead, aluminium and nickel are determined.
    • Magnetic iron wear particles in the form of the PQ-index can be used to draw conclusions regarding corrosive wear (non-magnetic) versus abrasive wear.
    • Additives such as calcium, zinc, phosphorous and sulphur are present in HLP oils containing zinc. Zinc-free oils contain only sulphur and phosphorus as elements. In the analysis, attention is given to the fact that zinc-containing and zinc-free HLP hydraulic fluids should not be mixed with each other, due to the risk of poor filtration characteristics resulting from zinc soap formation.
    • Any contaminants such as silicon, potassium, sodium or water that may be present indicate whether water, such as hard water from the cooling circuit which evaporates at a temperature of 80°C, has left its “hardening agents” and mineral content in the oil.
    • Comparison of the infrared spectrums of the fresh and used oil indicates the extent of oil aging and oxidation.
    • The viscosity at 40°C and 100°C and the viscosity index provide an indication of the additives and of oil aging and mixing.
    • The visual impression, odour and appearance allow a plausible diagnosis to be recognised in combination with the other values.

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