Marginally lubricated

8 Machining8.3 ReamingDX can be reamed satisfactorily by handwith a straight-fluted expanding reamer.For best results the reamer should besharp, the cut 0.025-0.050 mm and thefeed slow. Where hand reaming is notdesired machining speeds of about 0.05m/s are recommended with the cuts andfeeds as for boring.8.4 BroachingFig. 33 shows broaches suitable for finishingbushes up to 65 mm diameter. Thebroach should be used dry, at a speed of0.1-0.5 m/s.1.5 mmC dia - 3 mmDouble tooth cutter2LL3 mm rad polished1.5 mm rad5°0.75 mm x 45°1.5 mm rad´C´dia´B´dia´ ´B 1´dia ´A´diaDetail of tooth form1.5 mm0.75 mm radPitch P6 mm1.5 mm radpolished2°45° 45°1.5 mm0.75 mm land5°Alternative - single tooth cutter2LL´C´dia´B´dia´A´dia30Bush Width PitchBOver ToP10 13 313 20 420 30 530 50 5.550 70 670 95 795 130 8Diameter´A´´B´´C´Min. ass. boreNominal boreNominal bore+0.013+0+0.038+0.025+0.015+0.005Min. ass. bore = D o min - 2 x s 3 maxNominal bore = min. finished bore-0.065´B 1´* Nominal bore-0.076Fig. 33: Suitable broaches for DXUse the single tooth version where thebush is less than 25 mm long, and the doubletooth broach for longer bushes or fortwo or more bushes together.If it is necessary to make up a special formof broach the following points should benoted:Min. length ofPilot GuideL minSingle bush B + 62 or moreB + 6 + bush spacingbushes in line* First tooth of double tooth cutter• Adequate provision should be made forlocating the bush by providing a pilot tosuit the bore of the bush when pressedhome. A rear support shoulder shouldlocate in the broached bore of the bushafter cutting. Alternatively, special guidesmay be provided external to the workpiece.• If two bushes are to be broached in line,