Test Your Knowledge

Some unfrequently asked questions (Click on question to reveal the answer)

1) What is the main characteristic of alloy 7020?

It regains its properties after welding

2) Suggest an application where alloy 6351 might be used and why

Bicycle wheels, it retains its properties after forming

3) Name three different ways of joining aluminium to sections to each other

Clip fit, slide fit, ball and socket.

4) Where would a Vignole rail be used?

As a rail or tram track

5) Work out the cross sectional area of a 27mm x 5mm rectangular bar and its weight per metre

0.366 kgm/135 square mm

6) What principle issue occurs when extruding multiple hollow sections?

Differential cooling. The chambers cool at different rates; this can cause distortion and create heat-affected areas that impact negatively on surface finishing

7) Give two benefits of using alloy 6005 against alloy 6082

It is easier to extrude, is spray cooled as opposed to immersed; therefore has less distortion and offers better surface finishing

8) Give one advantage of using alloy 6082 over alloy 6005

It has marginally better mechanical properties

9) What beneficial characteristic does alloy 6063A possess?

It flexes well, which is ideal for small louvers and some clip fits

10) Is aluminium magnetic non magnetic or paramagnetic?


11) Define anodising

It is the controlled precipitation of the natural oxidisation process

12) What is Spectra Colour?

It is a form of anodising process that achieves different colours within the same tank

13) What is the difference between Bronze anodising and Bronze Anolok?

The former is tin based the latter cobalt based (giving much greater light fastness)

14) What is the current EN standard offered by most European Extruders?

BS EN 755 Part 9

15) Name two types of common corrosion

15) Pitting, atmospheric, crevice, galvanic

16) Why is highly efficient alocrom no longer used as a pre treatment for polyester coating?

It is a carcinogenic

17) Name two of the five tests paint samples experience to achieve Qualicoat status

Cross hatch, impact, form, centrifugal

18) Name two important features that facilitate ease of extruding

Symmetry and uniform thickness are amongst the main ones

19) What alloy range is most suitable for marine applications?

5000 series

20) What element enables this?


21) Name one benefit of punching over machining

Lower unit cost

22) Name one disadvantage of machining over punching

No tooling rapid start up

23) What is a DXF file and what does it stand for

It is a Drawing Interchange Format cad file that can be interpreted by any Cad Program

24) What is the difference between a countersunk hole and a counter bored one?

Countersunk is angled counter bored is straight

25) Suggest a potential difficulty when considering post anodising intensively machined components.

It changes the holes sizes and tap sizes if not masked

26) What is the coefficient of linear expansion of aluminium?

24 x 10-6

27) What is the preferred depth to width ration on extrusion?

3.5:1…example if the distance between the legs of a channel is 10mm the preferred maximum height of the legs would be 35mm

28) What is the ideal angle that screw ports open at?


29) What is the approximate melting point of aluminium?

> 620°

30) Is aluminium a superior or inferior conductor of heat than copper?

Superior it has the same conductivity at half the weight

31) What applications would you expect alloy 6463 to be used in?

High spec cookers, shower cubicles and lighting

32) What does a Renishaw probe do?

It is an inspection tool/aid that verifies accuracy of machined components on CNC machines

33) What does an IP rating refer to?

Water ingress often seen on extruded enclosures

34) What is a Romidot

It is an inspection tool that compares input cad geometry against the physical material

35) In what type of circumstances would you expect to find extrusion alloy 1050A?

An electrical one

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