Improvement of Manufacturing Tools

Dr Kocańda

Spis treści

LECTURE 2              3

Grinding              3

Carbonising              3

Nitriding              3

Electro Discharge machine              3

Phase transformation              4

LECTURE 3              5

Different transformations              5

LECTURE 4              8

Carbon tool Steel for cold work              8

Alloyed tool steel for cold work              9

Alloyed tool Steels for hot work              9

Insert WCL              10

High speed Steel              10

Powder metallurgy              11

Maraging Steel              13

WC – Tungsten Carbides              13

Combinations of carbides and steels              13

FerroTiC              13

Different materials for tools              13

LECTURE 2

Grinding

Surface finished

Cutting different kind of rods

Edge should be sharp

Surface under great pressure

Grinding (szlifowanie) – tool is sticking with material under high pressure

Experiencing friction (tarcie)

Work of friction which is changed into heat

Material under grinding tool is heated

Required cooling device (with water or oil)

Parameters of grinding – number of cycles (n) and depth of grinding

Hard to maintain stabile temperature

During process material is fracturing but only at the surface

Observing thermal stresses

Also mechanical stresses which would cause high fractures of the material of tool

Carbonising

Resistance to wear (odporność na ścieranie)

Solution: Carbonising treatment – to increase resistance to wear

During heating treatment there is change from austenite to martensite and the surface is then very strong

Lower parts of materials ale places where stresses are concentrating

Nitriding

Nitrides are formed in high temperature

We need to be careful with temperature of process

Electro Discharge machine

Die (matryca)

Die is made of Cu or C

Parameters of EDM: J, V,

Wrong parameters can cause fractures, i.e. when making simple holes

Material then became very brittle (kruchy)

There is created layer called dendrytes – very brittle

Second layer is called untempered martensite

Third layer is highly tempered

There is fourth – too fast :D

Between layers there are stresses

Phase transformation

Ferrite – Fe alpha

With high temperature – Austenite Fe gamma

When cooled with low speed – Ferrite

When cooled with high speed – Martensite

It’s hard to get martensite

High temperature is causing thermal stresses

This is making thermal compactions

In order to make martensite possible w/o thermal compactions we can add alloys to steel

In example we can add Chrome or Molybdenum

There two groups of that kind of alloys

First group – they form carbides: Fe, Mn, Cr, Mo, W, V, Ti

Second group which doesn’t form carbides: Ni, Si, Co, Al, Cu, N

M3C (3 atoms of metal and 1 with Carbon) -> Fe3C (cementite)

M7C3, M23C6, M6C, M2C, MC