The Taylor - Hobson -Talysurf Surface Roughness Tester

1. SUBJECT :-MATERIAL MEASUREMENT AND
METROLOGY(2141901)
TOPIC:-THE TAYLOR-HOBSON-TALYSURF SURFACE
ROUGHNESS TESTER
PREPARED BY:-
HARSH KAPADIA

2. The Taylor-Hobson-Talysurf surface roughness
tester:-
 This instrument is a stylus and skid type of instrument working on
carrier modulating principle.
 The variation in the surface profile is sensed by the probe , which
is attached to the armature.
 The gap between the armature and E-shaped arm varies according
to the surface profile and due to this amplitude of the AC current
flowing in the coil is modulated.
Construction:-
 As shown in figure ,the stylus is mounted on the armature , which
is pivoted at the central limb of an E-shaped soft iron head.
 The outer limbs of the head are provided with two induction coils
and a small air gap is left between the armature and outer limbs of
the head.

4. Working:-
 A downward movement of the stylus results in decreasing the
air gap of the primary coil and in an equal increase of the air
gap at the secondary coil.
 Thus the amplitude of the original A.C. current flowing in
the coils is modulated.
 The output of the bridge thus consists of modulation only as
shown in figure .
 This is further demodulated so that the current now is directly
proportional to the vertical displacement of the stylus only.
 The demodulated output is caused to operate a pen
recorder to produce a permanent record and the meter to
give a numerical assessment directly.
 The response of this instrument is more rapid and accurate
as compared to Tomlinson surface tester.

5.  Different uses of surface
roughness tester:-