Dr. D. Y. PATIL SCHOOL OF ENGINEERING & TECHNOLOGY

PRESENTATION ON MANUFACTURING PROCESS &MATERIAL SELECTION OF SCREW JACK

By,

Under the guidance of,Prof.

.

IntroductionScrew Jack

Screw jack is a portable device consisting of a screw mechanism used to raise or lower the load.

There are two types of jacks most commonly used,1] Hydraulic2] Mechanical

Parts of Screw Jack

1] FRAME2] SCREW3] NUT4] HANDLE5] CUP6] SET SCREW7] WASHER

FRAME Most of the times frame is conical in shape

and hollow internally to accommodate a nut & screw assembly.

MANUFACTURING PROCESS – The complex shape of frame leads us to use a ’Casting’ process for manufacturing.

For all this purpose to select a cast iron as material for frame.

a FG200 as material for frame such as it contains carbon precipitates as “graphite flakes” as graphite is soft in nature it improves its ability to resist a compressive load.

SCREW Screws is nothing but a member having

Helical groove around periphery of solid bar.

MANUFACTURING PROCESS - Square threads usually turned on lathes using single point cutting tool. It leads us to use free cutting steel.

“25C12S14 UNALLOED FREE CUTTING STEEL”. It indicates - 025% carbon, 1.2% manganese,

0.14%sulphur. Sulphur gives resistance to wear & 0.25%

carbon gives it sufficient strength to compensate weakness in roots. also easy in cutting due to manganese.

NUT As we know there always a relative motion

between screw and nut, which cause a friction. The friction causes wear if some material is used

for screw & nut it will wears both components. So one out of two has to be softer than other so as to ease of replacement.

The size & shape of screw is costlier than nut, so generally we use softer material for nut than screw.

Phosphor bronze is ideal material for nut which is a copper alloy having 0.2%phospher which increases tensile strength.

Advantages of phosphor bronze are, 1] Good corrosion resistance. 2] Low coefficient of friction

CUP It is used to hold object or Part .Shape of cup is again complex and

so economical to manufacture by Casting process.

material will be for manufacturing cup is cast iron with grade FG200.

HANDLEHandle is long circular

bar like structure, used to rotate nut.

Handle is subjected ti bending moments.

So plain carbon steel with 0.3%carbon i.e. 30C8 can be used to manufacture.

Reference

www.google.com www.nptel.com Books V B Bhandari etc

Thank You