8.4 Screw jointsGeneralThis section describes how to tighten the various types of screw joints on the IRB4600.The instructions and torque values are valid for screw joints comprised of metallicmaterials and do not apply to soft or brittle materials.UNBRAKO screwsUNBRAKO is a special type of screw recommended by ABB for certain screw joints.It features special surface treatment (Gleitmo as described below) and is extremelyresistant to fatigue.Whenever used, this is specified in the instructions, and in such cases, no othertype of replacement screw is allowed. Using other types of screws will void anywarranty and may potentially cause serious damage or injury.Gleitmo treated screwsGleitmo is a special surface treatment to reduce the friction when tightening thescrew joint. Screws treated with Gleitmo may be reused 3-4 times before the coatingdisappears. After this the screw must be discarded and replaced with a new one.When handling screws treated with Gleitmo, protective gloves of nitrile rubbertype should be used.Screws lubricated in other waysScrews lubricated with Molycote 1000 should only be used when specified in therepair, maintenance or installation procedure descriptions.In such cases, proceed as follows:1 Apply lubricant to the screw thread.2 Apply lubricant between the plain washer and screw head.3 Screw dimensions of M8 or larger must be tightened with a torque wrench.Screw dimensions of M6 or smaller may be tightened without a torque wrenchif this is done by trained and qualified personnel.Art. no.Lubricant11712016-618Molycote 1000 (molybdenum disulphide grease)Tightening torqueBefore tightening any screw, note the following:• Determine whether a standard tightening torque or special torque is to beapplied. The standard torques are specified in the following tables. Anyspecial torques are specified in the repair, maintenance or installationprocedure descriptions. Any special torque specified overrides the standardtorque!• Use the correct tightening torque for each type of screw joint.• Only use correctly calibrated torque keys.Continues on next page3HAC033453-001 Revision: H 337© Copyright 2009-2013 ABB. All rights reserved.8 Reference information8.4 Screw joints
