DESIGN OF GUIDE WAY /SLIDE WAYS
The guide ways of a machine tool ensure that the machine tool operative element (e.g. saddle, cross slide, etc.) carrying the cutting tool, ( or job), move along a predetermines path which may be a straight line (path0 as in lathe and drilling machines or a circular path as in a vertical torrent lathes. -
Guide ways with sliding friction are known as slide ways
Guide ways with rolling friction are known as anti frication ways -
Slide ways are either attached on the top of the bed or they are an integral part of the bed. Slide ways guide the movement of the slide. The slide is mounted on the sideways, sometimes, just as the railway train (I.e. slide) is one the rails (i.e. slid ways) (fig. 34.100. in a lathe, carriage and tails stock are slides. A slide carried the tools or the h job -
Slide way located and guide the slide and maintain the alignment of the guided parts (i.e. slides). The slides move thereby changing the position of the tool relative to the work pieces. Characteristic / requirement of slide ways
Accuracy of movement of the slide. It depends upon the accuracy with whit the slide ways are machined. The general tolerance for straightness of machine tool slide ways is 0 to 0.02. mm per 1000 mm. the slide should move in compliance with strictly straight line ( or circular) motion without slide rotation . to maintain accuracy, the ingress of foreign matter e.g. swage must be prevented and lubrication should be adequate 2.
Durability. The dies ways should retina the initial accuracy of travel of the slides over a specified period of operation. Sometime, to facilitate assembly, maintain accuracy and eliminate play between the slide ways and the slide, a gab strip is inserted in the slides Diagram
Adequate load carrying capacity
Reduced friction between the slide and slide ways
Freedom from unnecessary restraint
Prevention of sward accumulation and ease of slide ways and slides 10.
Effective lubrication. Slide surface should possess minute surface should possess minute surface depression to retain the lubricating oil which otherwise may get squeezed out. Slide ways may be lubricated through grease or oil nipples or by pumping the lubricating oil Martial for sideways
Slide way should possess adequate
Material used for making slide ways are
Grey cast iron
Grey cast iron: it is the most commonly used material for slide ways especially when the slide ways are made integral with the bed. Processes such as flame or induction hardening are used to increase the war resistance of cast iron slide ways 2.
Steel: when attached (i.e. screwed or welded) separately with the bed, the sideways are made up of steel that has been either indication hardened (52 to 58 RC). This ensures high resistance to wear 3.
Plastics: plastic have been sued for slide ways in heavy machines tools (e.g. large planning machined) and where rigidity of the slides is comparatively low. This leads to the non uniformity in the distribution of pressure on the sideway surface and, therefore, jamming may result, especially, when lubrication is insufficient NB. Plastic strip is fix the slide
Plastics possess antis coring and anticorrosive propertied ii.
Fabrication is easy
Friction against sliding is less
Coefficient of thermal conductivity is low
Thermal distortion is more
Strength and hardness are low
There is a tendency to swell by absorbing oil
Plastic sideways are affected by humidity
The speed of slinging is low
Types of slide ways
Various typed of slide ways are
combinatorial Slide ways
the shapes of the slide ways are...
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