Parting and Grooving. External operations : 1. Parting off, 2. Grooving, 3. Turning, 4. Profiling, 5. Undercutting, 6. Face-grooving, 7.

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1 PRTIN N ROOVIN

2 Parting and rooving utting off and making grooves In parting operations, the objective is to seperate, as efficiently and reliably as possible. one part of the workpiece from the other. straight cut is made to a depth equalling the workpiece radius of a bar. In grooving operations, the principle is the same but with the difference that the cut is shallower and not taken to the centre. rooving operations are less sensitive in some respects because the grooves are usually not as deep, instead shape, accuracy and surface finish are often demands that need more attention. The machining process can be compared to a facing operation in turning, where the tool is fed radially into the centre, the difference being that in the parting operation, the tool is a thin blade making a narrow groove. There is material on both sides of the tool and thus the material to be cut through should be as little as possible and the width of the cutting edge should be small. This makes considerable demands on the performance, chip forming and stability of the parting tool. s the tool moves to the centre, and if the spindle speed is kept the same, the cutting speed will gradually decrease until it reaches zero at the centre. In Nlathes, the spindle speed is increased as the tool moves towards the centre. ny decrease in cutting speed is disadvantageous for the tool and one that can make severe demands on the cutting edge. s the edge approaches the centre, pressure increases as the tool is fed in at the decreasing cutting speed. hip evacuation is also a critical factor in parting operations. There is little opportunity of breaking chips in the confined space as the tool moves deeper. The chip-formation geometry of the cutting edge is devoted largely to form the chip in order for it to be evacuated smoothly. onsequences of poor performance in this respect are chip obstruction which leads to poor surface quality and chip jamming, leading to tool breakdown. 6 xternal operations : 1. Parting off, 2. rooving, 3. Turning, 4. Profiling, 5. Undercutting, 6. ace-grooving, 7. Threading

3 Machining factors Modern parting and grooving tools are, in addition to being very productive, also versatile. Most types of turning operations can be carried out with today s indexable insert tools. enerally, operations that do not require the large overhang that the adjustable blade type of tool offers, should be performed by the shank type or oromant apto tool, where the blade is an integrated part of the toolholder. Maximum rigidity, which is vital in parting, grooving, profiling and turning operations, is offered by this design. owever, the adjustable blade type tool does have an added advantage in that it offers the flexibilty of having adjustable overhang when different diameters and deep groove-depths are involved. It provides the shortest overhang with maximum stability for different bar diameters. The main cutting data and tool definitions in parting and grooving operations are: cutting speed (vc) which is the surface speed at the cutting edge Parting and grooving tools for different applications. spindle speed (n), the machine spindle revolutions per minute the straight, radial feed towards the centre (fnx) the radial depth of cut capability of the tool (ar) - the distance from outer diameter to the centre or bottom of groove V c f nx a r 3

4 Parting off Tool Selection enerally, minimize tool deflection and vibration tendencies through : - selecting the toolholder or blade with the smallest overhang, - choosing the largest possible shank dimensions on the toolholder - choosing the blade or toolholder with the largest possible insert seat (width) - choosing a blade height which is at least equal to the insertion length irst tool choice for parting operations should be tool blocks with blades, where the blade can be adjusted to optimize the tool reach/tool overhang. Screwclamp type insert clamping is the best choice from a stability point of view. reinforced toolholder will increase stability even more. The tool overhang should not exceed 8 times the insert width. R N L Tool block with spring-clamp tool blade for tool overhang adjustment and a reinforced blade. ifferent entering angles φ r have their uses: The neutral insert provides a strong cutting edge with the cutting forces being mainly radial, providing a stable cutting action, good chip formation and tool-life, and excellent results through alignment in cut. There are three types : neutral (N), where the cutting edge is at right angles to the feed direction of the tool with an entering angle of zero degrees; right (R) and left (L) handed inserts - each having an entering angle of a few degrees. n entering angle of a few degrees is, however, useful in parting operations in that the end of cut can be finished more advantageously. If a neutral insert is used, the part of the workpiece that has been cut off is left with a very small diameter protrusion (pip). parting tool with an entering angle can be used to remove the pip when the cut part drops away. The hand of the insert is selected so that the leading corner of the cutting edge is next to the part being cut off. The pip is then left on the workpiece while still in the machine and removed by the cutting edge that faces through to the centre. urrs will also be reduced through the effect of the entering angle. Inserts with an entering angle of 5 degrees are available in, M and R geometries. Inserts with 10 and 15 degrees entering angles are available in S geometry. ntering angles. utting off the pip in parting operations. Pip and burr free machining. 4

5 To avoid or minimize pips and burrs, use a sharp (ground) insert, right- or lefthanded ( and S for instance) with the smallest possible angle. lthough a large angle reduces pips and burrs, the tendency is for the cut to be more uneven and surface finish and tool-life not to be optimum. The size of the pip is also affected by how the workpiece part that is cut off breaks away because of the centrifugal forces. The size and length of this part affects the point of parting and for this reason, the size of the pip can be minimized by supporting the growing instability of the workpiece being cut off. Select dedicated inserts for the operation in question for best performance and results. or large depths of penetration in parting, the double-ended blade solution is recommended. or parting small diameter bars or components, cutting forces should be minimized through selecting small insert widths and sharp cutting edges (such as geoemtries S and ). Parting off with orout 2. When parting thin-walled tubes, minimize the cutting forces by using sharp inserts with the smallest posible width, for instance and S geometries. The choice of insert-width is a compromise between tool strength and stability on the one hand and workpiece material saving and lower cutting forces on the other. pplication factors or maximum stability during machining, screw-clamp toolholders are always recommended when any axial machining (turning) is involved. spring-clamp tool is only recommended for radial machining, such as in parting off. Recommended torque values are provided for the screw-clamp type tools. It is important to follow these and not to over-tighten the screw the maximum torque is about 50% higher than what the table indicators. eed rate reduction is often advantageous for performance when machining towards the centre to minimize the pressure on the cutting edge. lso because of the reducing pip size, the feed should be reduced by up to 75% when approaching the centre, around 2 mm before the part comes off. utting data should be adapted so as to minimize possible vibration. This may lead to the tool-life being doubled. eed reduction towards centre. Stop the parting off operation before reaching the centre because, due to its weight, the disc in question could fall off before completion. Leave the pip on the bar to be faced off with a conventional tool. Spring-clamp tool for radial cuts and screw-clamp tool for radial and axial cuts. 5

6 widths (la) can be used to improve stability but at the expense of wasting more material in the cutting off operation. The largest possible tool-shank (h and b dimensions) should be chosen as well as the largest blade height (h1) and insert seat width (la). utting into a drilled hole correctly. Important right-angle positioning of tool. When parting a bar with a drilled hole, ensure that the depth of the hole is sufficient for the width of the insert. If the hole has been drilled with a pointed drill and the parting tool has to enter the coned part of the hole, the blade may deflect, generating excess forces on one corner of the insert and which may lead to insert chipping and inconsistent tool-life. entre-height accuracy of cutting edge is important. Tool positioning is an important factor for success in parting and grooving operations. It is vital for the cutting tool to be mounted accurately at a right angle to the centre line of the workpiece to be machined. eviations will mean added stresses on the blade as it is fed into the workpiece and result in machined surfaces that are not flat. Vibrations arise and chip formation is often disadvantageous. The tool position as regards the centre height of the cutting edge is also important. eviations from the workpiece centre line should not be more than +/- 0.1 mm. xcessive deviations change the cutting action with higher cutting forces. This can also lead to added friction between tool and workpiece resulting in reduced tool-life which also affects the size of the pip. utting fluid should be used with copious amounts directed onto the cutting edge. oolant should be supplied constantly while the insert is engaged in cut. coolant adaptor can be mounted with the supply directed from above. or tool blocks with a parting blade, the coolant supply can be connected above or from either side of the block. Mounting an insert in the orout springclamp tool involves using an excentric key to open the insert seat for the insert to be pushed into place. Removing the insert involves a similar procedure to pulling the insert out of the seat. Mounting an insert in the Q-ut spring clamp should always be preceeded by applying a little coolant or oil on the insert seat to further increase the toolholder life. Use the special Q-ut key for mounting and removing inserts to avoid cutting edge damage. No pivot-holes are provided in either the 570-type exchangeable head tool (R/L ) for parting and face grooving. or these items, a small rubber mallet should be used to tap the insert into its position. The tip of the yellow key should be used to extract the insert. reating the best stability for the cutting tool set-up is especially important in parting and deep grooving operations. The tools involved have long thin blades which are necessary because of the need for accessibility. The overhang of the blade should be minimized with the smallest possible tool reach (ar) which means that the adjustable blade is, in many cases, the best alternative, even though the shank tool with integrated blade is the most rigid. Wider insert Typical clock-spring chips from parting off. utting fluid is important in parting and grooving. 6

7 rooving Turning Machining grooves has many similarities to parting off, especially deep grooves. lthough the same toolholder systems can be used for both parting and grooving in many instances, the insert geometries are dedicated to provide optimum performance and results. rooves vary : there are shallow grooves, deep grooves, wide grooves, external grooves, internal grooves and face grooves. or single grooves, a suitable insert is applied to match the size and limits while wider grooves can be machined in various ways. edicated insert geometries, for low and high feed applications, contribute towards optimizing the grooving operations by giving specific benefits. Machining a wide groove. Inserts for single grooving cuts and shallow grooving toolholders. or single-cut grooving generally, straight cuts can be made for groove widths of up to 8 mm giving the best method, chip control and tool-life. Tailor Made inserts are made to match the specific groove size. hamfers can also be part of the programme. Insert geometry M is recommended for general groove turning and for precision grooving. Processes should be optimized in relation to the production volume. The T and insert geometries have Wiper design on the side in order to generate high surface finish on the sides of the groove. hamfering of the groove can be carried out with the orout 2 system using the corners of the grooving insert. or volume production, the Tailor made alternative of an insert that produces the complete form of the groove should be considered as this often halves the machining time. The most common methods of roughmachining wide grooves, or turning between shoulders, are : multiple grooving, plunge turning and ramping. separate finishing operation is usually required. - If the width of the groove is smaller than the depth, multiple grooving is the most suitable method. - If the width of the groove is larger than the depth, plunge turning is the best method. - If the bar or component in question is slender or weak, ramping is recommended. or multiple grooving (step-over grooving) cuts to make a wide groove, the widest possible insert should be used and in an alternative plunging-order. The best chip-control and tool-life is obtained by using an insert width leaving rings which are then removed. The insert corner is protected and chips are directed into the middle of the chipbreaker. Recommended ring width is 0.6 to 0.8 times the Multiple grooving, plunge turning and ramping are methods to make wide grooves. 7

8 ves in workpiece materials with poorer machinability. To achieve the best roughing results in the form of a flat groove-bottom with the best groove-side quality, see under Turning and Profiling. Multiple grooving a wide groove. Plunge turning a wide groove. Ramping of wide grooves, involves twice the number of cuts but is suitable for when the bar or component is slender or weak. Radial forces are smaller, thus generating less vibration tendencies. hip control is also good and notch wear is reduced especially when making groo- To acheive the best finishing results, care should be taken when machining the corners of the groove. s the insert cuts the radius of the corners, most of the tool movement will be along the z- axis. This produces a very thin chip at the front cutting edge which may lead to rubbing instead of cutting and hence vibration tendencies. To prevent this, the axial and radial depth of cut should be mm and the first cut should be made into the groove, axially, where the groove radius joins the flat bottom. Then optimize the process in relation to the batch sizes. The Wiper effect generates good surface finish with Ra values down to 0.2 microns. insert width. It is often more suitable for small batch production and face grooving. This is a flexible method which is quick to programme and geometry M is the first choice for this method. or plunge tuning of wide, shallow grooves, the axial turning depth should not be larger than 0.75 times the insert width. eometries T and TM are designed for axial and radial feed directions and are recommended for both plunging and ramping of grooves. hip control is usually advantageous. To improve the machining process and tool-life, lower the cutting forces prior to changing feed direction to minimize vibration tendencies, stop the feed in corners to minimize vibrations. Strive to make use of the three edgezones (two sides and one end) of each insert to maximize utilization. Turning operation. inish machining a wide groove. 8

9 irclip grooving The need for circlips on shaft and axle components is very common and there are two systems suitable for these operations. oth systems have specific widths for circlip grooves. irst choice is the three-edge T-Max U-Lock 154 system with groove widths of 1.15 to 4.15 mm for external and internal applications. There is a tool cost advantage with the 3 cutting edges. Second choice is the orout 2 system using the insert geometry with widths 1.85 to 5.15 mm for external applications. Undercutting Recesses for clearance, such as for subsequent grinding operations on various shafts and axles, require dedicated inserts with round cutting edges that are sharp and accurate. or this there are small and large applications. or the shallow recesses, orout 1 or 2 with RO and RM insert geometries are recommended. or deeper recesses, T-Max Q-ut system with insert geometry 4U is recommended. irclip grooving with U-Lock (left) and orout 2 (right). ace grooving Making grooves axially on the faces of components requires tools dedicated for the application. face grooving tool has to be made to clear the round groove which it is making the toolholder has to be curved. oth the inner and outer diameter of the groove needs to be taken into account for the tool to be accommodated. irst-cut diameter ranges are indicated for various tools. When a groove is machined in several cuts, only the first cut needs to be considered as the tool is then accomodated to machine smaller groove diameters. acegrooving or face grooving, the following general points apply : - minimize tool overhang to limit any vibration tendencies - keep the infeed rate low during the first cut to avoid chip jamming - start machining the largest diameter and work inwards to obtain the best chip control - if chip control during first cut is unsatisfactory, dwelling can be introduced. L R Undercutting hoice of R and L tools depending upon rotation. 9

10 Wider face grooves can be machined in different ways : 1. Roughing through multiple grooving cuts, where 0.5 to 0.8 times the insert width is used to open up the groove to the required width after the first cut. finishing cut can then be made along the sides of the grooves and the groove bottom face. The largest diameter should be cut first followed by work continuing inwards. The first cut is with chip control but not chipbreaking. The following cuts are with chipbreaking. When retracting, offset the insert slightly from inner edge of groove. 2. The second roughing method involves plunge cutting and finishing as in the previous method. The axial depth should not be deeper than 0.75 times the insert width. good indicator is that if the groove is wider than it is deep, plunge turning is recommended. If the groove is deeper than it is wide, multiple grooving is recommended. 3. inishing can also be performed according to three cuts : cut 1 within given diameter range and face towards the radius; cut 2 finish outer diameter and radius and face inwards; cut 3 finish the inner diameter to the correct groove dimension. If the inner side of the tool blade rubs against the groove side, make sure it is the correctly chosen tool for the diameter range in question, lower the tool slightly below the centre-line and make sure the tool is parallel to the axis of rotation ifferent methods of making wide face grooves a possible solution, especially when the tool overhang is 3-7 times the tool diameter. orout SL is a good solution where tool assemblies can be made to optimize the application. Solid and tuned adaptors are available within the SL-system. orout with dedicated insert geometries, M, TM and T are suitable for internal grooving or smaller holes (diameters below 25 mm) the T-Max Q-ut system with insert geometry 4 is recommended. Multiple grooving or plunge grooving, especially with narrow inserts, reduces vibration tendencies when making wide grooves. inishing operations can then be performed seperately. hip evacuation is facilitated by starting machining at the bottom of the hole and machining outwards. Use the best choice of right- or left-handed insert to direct chips especially in roughing. If the outer side of the tool blade rubs against the groove side, make sure the tool is correctly chosen for the diameter range in question, lift the tool slightly above the centre line and make sure the tool is parallel to the axis of rotation. Toolholder selection is critical for face grooving from the orout 1 and 2 systems as well as T-Max Q-ut and orout SL. or grooving depths of up to 4.5 mm, a special toolholder for shallow face grooves should be selected. Suitable inserts are grooving and turning insert geometries type M, acegrooving T and RM. or small first cut diameters, T-Max Q-ut 7 and 7P are suitable. Internal grooving Most of the methods for external grooving can be applied to internal grooving. Precautions may have to be considered, as with boring in general, to ensure chip evacuation and to minimize vibration tendencies. Tool size, overhang and set-up should be optimized and tuned bars be Internal grooving 10

11 Profile turning Turning and profiling Modern parting and grooving tool systems can also perform turning operations for which there are dedicated insert geometries. The stability of the orout system provides it with the capability of machining at high cutting data even when exposed to the radial forces during axial turning. When profiling of various shapes is required, the orout systems offers scope for rationalization since one tool can be used to replace right-hand and left-hand conventional tools. The roundshape inserts have dedicated geometries for these operations, for instance RM for medium feed rates and tougher machining conditions; RO for stainless steel and sticky workpiece materials and M, which is a sharp, positive profiling geometry for non-ferrous materials such as aluminium. R is recommended for hard hard steels and RS for finishing non-ferrous materials. The orout system offers unique stability with the rail seat design and the Wiper effect good surface finish. Tool deflection always occurs to some extent and some compensation may be necessary for the difference in diameter machined. The difference should be established and the tool drawn back so that the correct diameter can be machined. The adjoining diagram illustrates this process. screw-clamp toolholder should be selected for turning and profiling operations in view of achieving maximum stability. orout or Q-ut tool with the shortest possible tool accessibility (ar) should be applied (for Q-ut holder type 22). If for reasons of accessiblity this is not possible, apply a holder with a longer dimension (for Q-ut holder type 23) with cutting data reduced accordingly. neutral orout tool is suitable for both opening up or completing a recess, however, when machining with conventional tools a right- and left-hand tool is required to achieve the same result. In-copying is recommended to improve chip control, minimize tool wear and to eliminate the tendency of the insert working loose. To achieve perpendicular groove or recess walls, radial plunging should be carried out at each end, not one plunge followed by turning and out-feeding. ompensation on workpiece diameter. 11

12 Turning When it comes to roughing, limiting deflection is often an issue. orces on the insert should therefore be reduced prior to changing direction of cut according to the following sequence : 1. Infeed radially to the required depth of cut (ap max 0.75 times insert width) 2. Retract radially 0.1 mm 3. Turn axially to opposite shoulder position 4. Retract diagonally 0.5 mm to outside the component 5. eed axially to the end position (still 0.5 mm off the machined diameter) 6. Infeed radially to the required depth of cut. Retract radially 0.1 mm and continue the sequence for subsequent roughing passes. Turn axially in both directions to use both corners of the insert and to maximize tool-life. The machining of a wide groove can be performed using one tool, where two conventional tools might be needed. are should then be taken when machining the bottom radius or chamfer. s the insert contours the radius, most of the movement will be in the z-direction, which generates a thin chip at the front cutting edge. This may lead to rubbing between tool and component, rather than just cutting, and consequently more wear and vibration tendencies. ollowing the right sequence will help to prevent this from occurring. (See under finishing wide grooves). When machining wide, shallow grooves internally, the most suitable method is to plunge turn. owever, chip evacuation needs attention, making sure that chips are removed out of the hole and not jammed in the machining process. hips will always flow in the same direction as the feed and it is therefore recommended that the direction of feed is always towards the hole opening. or shallow grooving with toolholder, it is important that a shim giving an inclination angle of zero degrees is used in the toolholder. or machining small holes with toolholders not having shims, grooving bars should be used. Rough turning a wide groove. Right-hand inserts can be used in righthand external and left-hand internal toolholders. Left-hand inserts can be used in left-hand external and right-hand internal toolholders. When it comes to axial turning with orout tools, the Wiper effect makes it posible to generate a high surface finish (Ra values smaller than 0.5 microns can be achieved along with high bearing ratios). igh feed rates and O according f n1 = parallel cuts - max. chip thichness mm f n2 = radius plunging - 50% max. chip thickness to recommended levels should be used to ensure the best cutting action. If a sufficiently high feed is used with a small O (or low feed and large O ), sufficient deflection of the tool will take place to provide the insert with the clearance needed at the front cutting edge. ut if both feed and O are below recommended values, insert clearance may be insufficient and rubbing take place between insert and machined surface, giving rise to vibration tendencies and poor surface finish. solution, therfore, may be to use insert geoemtry T, having a concave cutting edge, which will minimize the contact between insert and workpiece. Insert geometries T (lower feed), TM (higher feed) and are designed to be used for axial turning. When plunging into or profiling corners with round inserts, a phenomenon known as wrap around is a problem that may occur. large part of the cutting edge is engaged in cut which leads to considerable pressure on the insert. If the feed rate is reduced excessively, however, vibration tendencies are generated. The problem is usually solved by applying the smallest possible insert radius in relation to the radius to be machined on the component. good starting point is for the feed rate when plunging into the radius to be 50% of that applied for the axial cut. If the insert radius has to be the same as that of the workpiece, introduce micro-stops (dwelling) which shortens chip length and breaks any vibration tendencies. Turning corners with round inserts. Solving wrap around effect in plunging. 12

13 Selecting tools for Parting and rooving ow to choose your tool efine the type of operation and system to use Identify the operation: Parting xternal or internal grooving, face grooving, shallow grooving xternal or internal turning Undercutting, profiling and choosing the most suitable system for it. (See Tool selection for parting and grooving tools) Select the insert geometry and grade hoose the insert geometry and grade. hoose your insert size on the corresponding ordering page. (See Insert geometries and grades) Select the tooling system and type of holder hoose oromant apto or shank tool, depending on clamping possibilities in turret/spindle. hoose the right holder size on the corresponding ordering page. The insert seat must correspond to the size of the insert. (See Selecting toolholder types) 4 orout XS Select cutting data ind the recommended feed for selected insert chosen. hoose the recommended cutting speed. (See speed and feed recommendations for parting and grooving geometries) Tooling alternatives for Parting and rooving When parting and grooving the inserts are often fed deep into the material, which sets high demands on accessibility. This means that the tools used are generally narrow and therefore the length of the tool increases as the diameter increases. Tools and tooling systems with high stability is therefore important. onventional turrets xternal oromant apto integrated multi-task machines lade Shank tool oromant apto unit Internal Steel shank boring bar and oromant apto adaptor utting head with bar in steel, carbide reinforced or tuned Steel shank boring bar 13

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