Maintenance of Machine tools

Nizwa College of Technology

Prepared By

Dr.K.Elangovan

Maintenance of Machine tools

Objective :

• Equipments and machine tools are very

important component of production activity

• Break down of machines resulted in reduced production and it will be great loss

• It is very important to maintain machine tools to minimize loss and to improve the production

MaintenanceDefinition

Maintenance is the process of keeping the machine and equipment in good working condition so that the efficiency

and life of the machine is increased

Advantages of good maintenance

Increased life of the machine

Ensured quality of the product

No production loss

Machinery is not damaged

Disadvantages of bad maintenance

Loss of production

More wastage of material

Reduced life

Leads to accidents

Cost of production is increased

Lathe maintenance

The lathe is a precision machine tool and must be treated with great care. Regular cleaning and maintenance will help to assure that the lathe will maintain its service life and accuracy for many years

Lathe maintenance involves maintenance of

• Drive belts• Gib Adjustment( cross slide, Compound slide)• Wipers Pads• Adjusting the Tailstock Clamp

Drive belts

Removal of guard Checking belt Tension

Adjusting belt tension• Drive belts come in matched sets and should only be

replaced with a matched set of belts.• Visually inspect the drive belts for excessive wear and

cracking. • If you notice that one or more of the drive belts appear

to be excessively worn replace it with new one • Check the belt tension by applying finger pressure to

each belt at a point midway between the two pulleys • For correct tension a deflection of about 6-8mm

should be evident in each belt. • If the amount of deflection is more than 6-8mm in any

one or more of the belts adjust it with belt tensioner

Gib Adjustment• All lathes employ precision slide ways.• The saddle, cross slide, and the

compound slide all ride along a box slide way or dovetail slide way

• After time the parts that ride along the slide ways begin to wear

• To compensate for this wear, machine tools are equipped with adjustable parts called gibs that allow you to eliminate the space that has been created by the wear between the slide ways

Gib Adjustment

Cross slide (Tapered Gib)

Gib Adjustment Procedure

• The procedure is to first loosen the similar gib screw in the rear face of the tool slide

• Then re-tighten the front screw to lock or adjust the Gib in its new position

• After making the adjustment, traverse the compound slide over its entire travel to be sure of smooth, even operation

Cross slide (Tapered Gib)

Tapered gib with screws Front gib screw

Compound slide (straight Gib)

• There are two types of gibs, straight gibs and tapered gibs

• Straight gibs are adjusted by screws spaced out along the length of the gib.

• The screws push the gib in to create more contact with the sliding mechanisms

Wipers Pads

Wipers Pads• Wipers are designed to keep out small chips and

dirt between the slides and the ways. • Wipers are saturated with oil to catch the fine

particles of dirt or debris before they get between the two sliding surfaces.

• The wipers should be removed, cleaned, and re-saturated with oil regularly.

• Never use compressed air for cleaning a lathe Compressed air will push the fine particles trapped in the wiper between the mating surfaces of the slides, causing premature wear on these precision surfaces

Scheduled maintenance

• Maintenance carried out in accordance with the schedule defined by the manufacturer of the machine

• Usually carried out in predetermined dates

• It involves inspection, Cleaning, lubrication, repairing and replacing the parts of the machine as per the recommendations of the manufacturer

Scheduled maintenance- LatheDaily- Cleaning chips from carriage, cross slide, compound rest and bed

- Check the head stock oil level through inspection glass

Weekly

-Check auto drain on filter regulator

-Clean out small chip catch pan in coolant tank

Monthly

-Lubricate the way covers

-Remove pump from coolant tank and clean it

-Check the gear box oil level, top up if necessary

Six months

-Remove the coolant and thoroughly clean the coolant tank

-Replace the hydraulic unit oil filter

- Check all hoses and lubrication lines for cracking

Annually

-Replace gear box oil

-Check and replace drive belts