Page 307 - Mechanical Engineer's Data Handbook

GENERAL DATA 295

Screws

The term 'screw' is applied to a wide range of threaded
fasteners used with metal, wood, plastin, etc. Screws
have a variety of types of head and are made in many
materials (steel, brass, nylon, etc.), some are plated.
U'dEiPB Nuts are usually hexagonal, but may be square or
Small screws usually have %A threads and special
threads are used for wood and self-tapping screws. 0.2.2 Nuts ad washers

round. Steel hexagon nuts may be 'black' or 'bright'
and have one or both faces chamfered. Washers are
used to distribute load and prevent damage to a
surface. They are mostly of steel, but brass, copper,
Cheese Rolnd Camtem~nkFWstw I- aluminium, fibre, leather and plastin are used.
heedp head M(W) head (Ormi8d A wide variety of lock washers and locking devices
flat filhster) counlsrsunk)
R
head are available, including adhesives such as 'Loctite'.
skttedheadmaoMnescter*s l~"3o"l 309 300

f
f

M

Square nut '

Cap nut
(cmwn nut.
dome nut)

Roundhead Countmunk CmdIeed
head (PhilHps rscass)
sen-tapping screws