DEPRAG SCHULZ GMBH U. CO
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Special Edition Preventive maintenance and repair of air-operated tools Screwdriving technology Automation Air motors Air tools D 0090 E 2.2008 Content 1. In our own words 3. Maintenance Intervals 6. Closing Comments 1.1 Preventive Maintenance - why? 4. Air-operated tool repair 7. Appendix 2. Air preparation 4.1 DEPRAG repair or 7.1 General repair tools 2.1 Air quality maintenance procedure 7.2 Tachometer 2.2 The correct operating air 4.2 The do-it-yourself repair pressure 4.3 General repair tips 2.3 Lubricated or non-lubricated operation of tools 5. Repair Training Courses 1. In our own words Dear customer, 1.1 Preventive Maintenance - why? by selecting a DEPRAG product, you have The benefit of preventive maintenance is acquired a tool, which was developed and without question. An unforeseen machi- manufactured for use in a heavy industrial nery breakdown is accompanied by a pro- environment. Since 1931, we have amassed duction shutdown, a loss of income and experience in manufacturing air-operated may even force a delivery limitation. machines and screwdriving systems. Correct maintenance, as well as properly We produce a variety of air-operated planned and precise implementation of machines such as screwdrivers, drills, grin- necessary repair, saves time and money. ders, motors, hammers and much more utilizing the most modern production The following implementations regarding machinery. To cover all imaginable screw the operation and maintenance of air-ope- joint applications, we offer, in addition to rated tools can only serve as a general the standard screwdrivers, electric hand- guide, because of the extensive spectrum held screwdrivers as well as freely pro- of DEPRAG air tools. grammable electric screwdriver spindles. Further information can be found in the Regarding special machinery technology, operating manuals of the respective tools we design and manufacture semi and which are available from DEPRAG either in turn key automatic screwdriving-systems, printed version or as pdf-files. with and without screwfeeding, for screw- assembly and handling tasks of all types. The practical use of our products extends from the simple hand tool to the complete screwdriving robotic cell as implemented in the automobile industry. Since 1996, DEPRAG’s Amberg facility has been certified according to DIN EN ISO 9001 in all operational areas. DEPRAG has bran- ches in China, France, Scandinavia, the Czech Republic, the USA and the United Kingdom and sales offices in almost all industrial countries worldwide who provide distribution and customer service. 2 2. Air Preparation 2.1 Air Quality The quality of the compressed air is a cri- tical factor for the lifespan of an air tool. The integration of a water separator as well as a central air dryer protects not only the air system, but also the airtool from corrosion. The use of an air filter is just as important. Dirty air can block the vanes and damage the motor. In regard to air-quality according to ISO 8573-1, we recommend: Class Residue of Oil Content Residue of Dust Residue of Water particle pressure mg/m3 oz./cu.ft. size mm mg/m3 oz./cu.ft. dew-point °C g/m3 oz./cu.ft. Dry Air 3 1 1.03 · 10-6 0.005 5 5.14 · 10-6 -20 0,88 0.90 · 10-3 Lubricated Air 4 5 5.14 · 10-6 0.015 8 8.22 · 10-6 +3 6 6.17 · 10-3 To attain the proper air quality, we recom- mend the DEPRAG maintenance units with 1/4” to 11/2” connection threads and a corresponding airflow. A regular inspection of the air filter for impurities and a lubricator volume adjustment is necessary. 3 Power (P) % Speed (n) % Torque (M) % Air-Consumption (Q) % 130 120 110 Nominal-Power Nominal-Speed 100 Nominal-Torque 90 n Air-Consumption 80 Q 70 M 60 50 P 40 30 6 bar Nominal-Pressure 20 10 Pressure (p) bar 34567 Pressure (p) Power (P) Speed (n) Torque (M) Air-Consumpt. (Q) bar / PSI % % % % 7 / 99 121 103 117 117 6 / 85 100 100 100 100 5 / 71 77 95 83 83 4 / 57 55 87 67 67 3 / 42 37 74 50 50 Picture 1: effect of the operational pressure 2.2 The correct operating air pressure An often-underrated factor is the use of the However, if a pressure gauge is connected 2.2.2 Air pressure too high correct operating pressure. All statements directly ahead of the tool, airflow of only regarding power output, speed, torque and 3 bar/42 PSI is often the result. (In each Air pressure over 7 bar/99 PSI leads to air consumption normally refer to a nominal case, the required hose I.D. can be found increased wear and tear of the air tool. A pressure (air volume) of 6 bar/85 PSI or in your DEPRAG operating instruction pressure regulator with sufficient airflow 6.3 bar/90 PSI. Deviating from the correct booklet. The hose length should not must be integrated. pressure affects this data. exceed 3 meters/10 ft.). In addition, the danger of injury must be A performance loss of the air tools is the considered. With too high an air pressure, 2.2.1 Air pressure is too low consequence under these conditions. the idling speed of the tool increases, With screwdrivers, a ratcheting (stalling) which in the case of unregulated grinders Often, it is determined that the required occurs at limited airflow. Air pressure ver- can result in exceedance of the allowable air quality is in fact available, but not the sus air tool performance is clarified in Pic- speed of the grinding insert. necessary air volume. ture 1. A broken grinding insert can cause consider- Air volume can be affected by fittings For example, just 55 % of the performance able harm to equipment and personnel! connected immediately following the main- is reached when there is a pressure drop tenance unit, such as air manifolds, pneu- from 6 to 4 bar/85 to 57 PSI. matic valves, quick connect couplers or air hoses with too small internal diameter. No considerable pressure drop could be determined on the pressure gauge of the maintenance unit while operating a tool. 4 1 drop of oil corresponds to approx. 15 mm3 Oil volume in mm3 to1 m3/35.3 cfm air-consumption 50 10 1 Nominal Power % 0 50 60 70 80 90 100 When using 1-2 drops of oil per 1 m3 / 35.3 cfm air-consumption, the optimal lifespan and performance of an air-motor is reached. Picture 2: effect of lubricated air 2.3 Lubricated or non-lubricated operation of tools 2.3.1 Dry Air – Lubrication prevents the direct contact, With the use of point-of-use oilers best life- and therefore the wear of internal parts time of screwdrivers at least necessary oil Generally, all DEPRAG air-operated Screw- slid ing against each other. Non-lubricated consumption is possible. Especially in cases drivers and Top Speed Grinders (gear operation can lead to elevated wear of where long operating durations are neces- motor) can be operated oilfree. However, internal parts. sary but no oil leakage should happen, this utilizing dry air can cause the speed and – Lubricated operation protects from cor- system represents a very good compro- performance of vane driven tools to be rosion. Because of the water content of mise between the restrictions of perfectly reduced by as much as 20 %. Under un - the compressed air, air tools are particu- oil-free use and the problems caused with favorable conditions, the maintenance inter- larly corrosion susceptible. An oil film regular oilers and the fine oil mist. vals may also be reduced when tool is ope- coating on the internal parts protects rated with dry air. from corrosion. Here the oilers should be adjusted so that With all other remaining air-tools, refer to – Lubricated air improves the motor insu- the oil volume is approximately 1 - 2 drops the operating instruction booklet, to ascer- lation. DEPRAG air-tools are machined of oil per 1 m3/35.3 cfm air consumption. tain if oilfree operation is permissible. to production quality standards and More oil is to no advantage; it only increases On special request, all rotational tools can close tolerances. The smaller the gap, the oil usage and becomes an unnecessary be equipped for oilfree operation. the smaller the air leak and performance burden for the environment. loss. A lubricant in the gap assures high performance. Impact tools such as hammers and scalers 2.3.2 Lubricated Air should only be operated with lubricated air. We recommend only the lubricant approved If the application condition permits the use by us [special oil „DEPRAGOL” order no. Picture 2 shows the effect of dry and lubri- of lubrication, then an air tool should be 790081 E/F/G, available in 0.25/5/10 liters cated air in comparison to the performance operated with lubricated air. The following (0.07/1.3/2.6 gal.)] in connection with suit- of an air tool. advantages can be stated: able oiler, supplying the compressed air with a fine oil mist or for point-of-use oilers. 5 3. Maintenance Intervals Air operated machines are extremely – The screwdriver spindle is operated robust. The inner overpressure prevents oilfree. the penetration of dust and dirt. Normally, – The screwdriver spindle is operated only the low cost vanes require exchang- at its medium power level. ing as wear parts. An estimate of the time – The cycle time for one assembly period of required maintenance intervals is two seconds. C x T however, cannot be simply made.