Page 27 - 6748

(4) : removal of surface layers with multiple cutting wheel passes.
(5) : using oxy fuel (oxygen + combustible gas, often acetylene).

c Complete the following definitions using the words in the box.
abrasive wheel guillotine hole-saw kerf punch toothed blade
1 A punch makes holes by applying pressure to shear the material.
2 A makes straight cuts by applying pressure to shear the material.
3 A is the width of the saw cut.
4 A has sharp edges for cutting or milling.
5 A has a hard, rough surface for cutting or grinding.
6 A cuts a circular piece to remove an intact core of material.

7a Read the following extract of promotional literature from a leading producer of ultra-
high-pressure (UHP) waterjet cutting machines. In pairs, explain the phrases in bold.
FLOW
What makes waterjets such a popular cutting option?
Water jets require few secondary operations, produce net-shaped parts with no heat-affected
zone, heat distortion, or mechanical stresses caused by other cutting methods, can cut with a
narrow kerf, and can provide better usage of raw material since parts can be tightly nested. As
a result of the FlowMaster™ PC control system and intuitive operation, waterjets are extremely
easy to use.Typically, operators can be trained in hours and are producing high-quality parts in
hours. Additionally, waterjets can cut virtually any material, leaving a satin-smooth edge.

b 3.7 Evan is talking to Mr Barrett about UHP waterjet cutting. Read the conversation and
match the phrases in the box to the extracts (1-4).
heat-affected zone mechanical stresses narrow kerf net-shaped parts

Extract 1 Extract 3
Extract 2 Extract 4

1
Evan: So we use high-pressure waterjet cutting quite a lot. The good thing about it is you don't
need to do any finishing afterwards. The edges are virtually perfect. So they are especially good
when you have intricate shapes.
Mr Barrett: Which would be difficult to finish otherwise.
Evan: That’s right.
2
Mr Barrett: Saw blades are obviously useless when you're cutting curved shapes.
Evan: That's right. And when you're using any sort of abrasive technique for cutting metal, it
inevitably gets hot. And that can alter the properties of the metal around the cut, which can be a
problem in some situations.
3
Evan: The other problem with abrasive cutting is it exerts shear forces near the cut. So sawing is
not the best solution if you want to avoid altering the material.
Mr Barrett: The same applies to guillotining, presumably.
Evan: It does, yes.
4
Mr Barrett: It’s amazing to think that a waterjet can cut through steel. You could imagine
watercutting timber or relatively soft material, but... Evan: No, it’s ideal for metals. Actually, it’s
not just water that’s used. They sometimes add an abrasive powder to the water to increase the
cutting power.

25