Mechanical Engineering Technology.

Lesson Topic: Files.

ObjectivesAt the end of the lesson students should be able

to:1.State the uses of files.2.Identify the parts of files3.Identify various shapes of files4.State and define three methods of filing.5.State how to care for files6.Explain some terms used in filing.7.Use the file to shape metal.

WELCOME

FILESFILES ARE COMMONLY USED IN MECHANICAL ENGINEERING TECHNOLOGY FOR SHAPING WORK.THEY ARE MADE OF HIGH CARBON STEEL WHICH IS HARDENED AND TEMPERED.FILES ARE MADE IN VARIOUS SIZES AND SHAPES.

Parts of the file. length

tip shoulder

tang

ferrule handleteeth

Shape of filesCROSS SECTIONS

flat Half roundround

knifetriangularsquare

hand

TYPES OF FILESTHE HAND FILE IS ALSO CALLED THE SAFE EDGE FILE.IT IS PARALLEL THROUGHOUT ITS LENGTH, HAS ONE EDGE (SAFE) WITHOUT TEETH AND IS USED FOR GENERAL PURPOSES.

THE FLAT FILE IS PARALLEL FOR TWO THIRD OF ITS LENGTH AND HAS TEETH ON ALL FOUR SIDES. IT IS USED FOR GENERAL PURPOSES.

Care of files.Never use a file without a handleClean the teeth as soon as they become pinned.Keep files in a dry place.Never use the file as a hammer.Never allow the file to slip over the work when filing.Never use a small file when a large one can do the work better.

Filing Terms.There are two common terms used in filing;The cut of the file.The grade of the file.

The cut of the fileThe cut of the file indicates the particular way in which the teeth are cut. They may be single cut, double cut or rasp cut.

single double rasp

THE GRADE OF THE FILE.

THIS INDICATES THE DEGREE OF COARSENESS OF THE TEETH.THE GRADES BEING; ROUGH, BASTARD, SMOOTH OR DEAD SMOOTH.

METHODS OF FILINGCROSS FILINGDRAW FILINGPROFILING

CROSS FILINGTHIS METHOD IS USED FOR ROUGHING DOWN.THIS IS DONE BY HOLDING THE FILE AT THE TIP AND AT THE HANDLE, PUSHING IT ACROSS THE SURFACE OF THE WORK.

DRAW FILINGTHIS METHOD IS USED WHEN FINISHING A SURFACE AND IS USUALLY DONE AFTER CROSS FILING.THE FILE IS HELD AT RIGHT ANGLE TO THE WORK AND AS CLOSE TOGETHER AS POSSIBLE THEN PUSHED BACK AND FORTH.

PRO FILINGTHIS METHOD IS USED TO PRODUCE CURVES ON WORK. THE CURVES MAY BE CONVEX OR CONCAVE.

CONCAVE FILINGIN CONCAVE FILING THE FILE IS TWISTED AND PUSHED FORWARD. A ROUND OR HALF ROUND FILE MAY BE USED.

CONVEX FILINGIN CONVEX FILING THE TIP OF THE FILE MOVES FORWARD AND UP WHILE THE HANDLE MOVES FORWARD AND DOWN.A FLAT, HAND OR HALF ROUND FILE MAY BE USED.

USING A SAFE EDGE FILETO CUT A CORNER

SAFE EDGE FILE

WORK

FILE

EDGE NOT TO BE DAMAGED

File CardWhen filing the soft metals, the small pieces of metal will tend to clog the teeth. If the file is not cleaned, this small piece of metal will scratch on the surface of the work. We call it pinning.

This case is frequently appeared when applying a new smooth file on the soft metals. The pinning can be removed with a File Card.

File Card

File Card

QUIZIF THE STATEMENT IS TRUE SELECT “T”, IF FALSE SELECT “F”.

1 FILE BLADES ARE MADE FROM HIGH CARBON STEEL. 2 THE LENGTH OF THE FILE IS MEASURED FROM THE TIP TO THE

TANG.3 THE HAND FILE IS THE SAME AS THE SAFE EDGED FILE.4 AS A RULE THE FILE TEETH SHOULD BE CLEANED AS SOON AS

THEY BECOME PINNED.5 IN DRAW FILING THE FILE IS HELD AT 90 DEGREES TO THE WORK.6 THE CUT OF THE FILE IS THE SIDE OF THE FILE.7 THE GRADE OF THE FILE IS THE COARSENESS OF THE TEETH.8 IN CONVEX FILING THE TIP OF THE FILE MOVES FORWARD AND

DOWN.9 A DOUBLE CUT FILE IS MORE SUITABLE FOR ROUGHING A PIECE OF

WORK.10 THE FILE SHOULD NOT BE STORED IN WATER TO KEEPIT COOL.