Page 573 - Dormer
P. 573

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








       572
   568   569   570   571   572   573   574   575   576   577   578