Page 573 - Dormer

GENERAL HINTS

TROUBLE SHOOTING WHEN TAPPING

PROBLEM CAUSE REMEDY
Oversize Incorrect tolerance Choose a tap with lower thread tolerance
Incorrect axial feed rate Reduce feed rate by 5-10% or increase compression of tap
holder
Wrong type of tap for application Use spiral point for through hole or spiral flute for blind
hole. Use coated tool to prevent built up edge. Check
Catalogue or Product Selector for correct tool alternative

Tap not centered on the hole Check tap holder and position tap centre on the hole

Lack of lubrication Use good lubrication in order to prevent built up edge. See
lubricant section in technical handbook

Tap speed too slow Follow recommendation in Catalogue / Product Selector

Undersize Wrong type of tap for application Use spiral point for through hole or spiral flute for blind
hole. Use coated tool to prevent built up edge. Use tap with
higher rake angle. Check Catalogue or Product Selector
for correct tool alternative

Incorrect tolerance Choose a tap with higher tolerance, especially on material
with low oversize tendency, such as cast iron, stainless
steel
Incorrect or lack of lubricant Use good lubrication in order to prevent chip blockage
inside the hole. See lubricant section in technical handbook

Tap drill hole too small Increase drill diameter to the maximum value. Check
tapping size drill
Material closing in after tapping See recommendation in Catalogue / Product Selector for
correct tool alternative

Chipping Wrong type of tap for application Choose a tap with lower rake angle. Choose a tap with
longer chamfer. Use spiral point taps for through hole and
spiral flute for blind holes, in order to avoid chip blockage.
Check Catalogue or Product Selector for correct tool
alternative
Incorrect or lack of lubricant Use good lubrication in order to prevent built up edge. See
lubricant section in technical handbook

Taps hit bottom of hole Increase depth of drilling or decrease depth of tapping

Work hardening surface Reduce speed, use coated tool, use good lubrication.
See section for machining of stainless steel in technical
handbook
Swarf trapping on reversal Avoid sudden return of tap on reversal motion

Chamfer hits hole entrance Check axial position and reduce axial error of tap point on
hole centre

Tap drill hole too small Increase drill diameter to maximum value. Check tapping
size drill

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