The manufature of components in steel, aluminium and copper alloys by
cold forging production has increased ever since the 1950's. Typical p
rocesses are forward rod extrusion and backward can extrusion, upsetti
ng, ironing, tube extrusion and radial extrusion. The tribological con
ditions in cold forging are extremely severe due to large surface expa
nsion and normal pressure in the tool/workpiece interface combined wit
h elevated tool temperatures. Except for the more simple cold forging
operations successful production therefore requires advanced lubricati
on systems. The present paper gives a detailed description of the stat
e of art for lubricant systems for cold forging of C-steels and low al
loy steels as well as aluminium alloys including all the basic operati
ons such as cleaning of the slugs, application of eventual conversion
coating and lubrication. As regards cold forging of steel the conversi
on coatings are based on zinc phosphates but different requirements to
the coating properties have to be met in different cold forging opera
tions. This is obtained by adopting different oxidants leading to diff
erent composition, layer thickness and morphology of the conversion co
atings. Concerning aluminium unalloyed and softer alloys like the AA 1
000, 3000 and 6000 series can be cold forged with either grease, oil o
r zinc stearate whereas the harder alloys from series AA 2000, 5000 an
d 7000 require a conversion coating to carry the lubricant. Three diff
erent types of conversion coating are described, i.e. phosphate coatin
g, calcium aluminate coating and aluminium fluoride coating. Alternati
ve lubricants and their application are also described.