in a similar fashion to that of a y-cutter, creating a periodically scored surface – aer each cutter revo- lution – degenerating the milled surface texture, • Chipping due to vibration – as all of the inserts are not set the same, then the most prominent one will take the largest cuts on both the minor and periph- eral cutting edges, causing shock loading as the cut is engaged, thereby increasing cutter vibration and potential thermal eects 44 creating the likelihood of chipping here on the most exposed cutting inserts, • Rapid growth of wear – because of a prominently set and poorly positioned cutting insert in relation to the others in the cutter body, it will absorb the greatest cutting loads, which will lead to shortened tool life, this being exacerbated by pronounced vi- brational tendencies, resulting from unbalanced cutting forces and torque. NB All of these factors will contribute to a short- ened cutter life. Conversely, if the face milling cutter’s insert run-out is small, then a good surface nish and stable and predict- able tool life will result. Mounting and Adjusting Single-Blade Reamers e cutting head of a single-blade reamer was previ- ously illustrated in Fig. 74a. e replaceable blade is positioned longitudinally by a blade end stop and 44 ‘ermal fatigue’ , can be present when cutting is interrupted – as is the case for milling with a prominently exposed ce- mented carbide cutting insert. Numerous cracks are oen ob- served at 90° to the cutting edge and are oen termed: ‘Comb- cracks’ – due to their visual appearance to that of a typical hair-comb. ese cracks, are the result of alternating expan- sion and contraction of the surface layers as the cutting edge is heated during cutting, then cooled by conduction into its body during intervals between cuts. is very fast alternating heating and cooling cycle, develops the cracks normally from the hottest region of the rake face – this being some distance from the cutting edge, which tends to spread across this edge and down the insert’s ank face. Once these cracks become quite numerous, they can join up and promote partial tool edging to break away – creating cutting edge chipping. NB Today, many cemented carbide tooling manufacturers use structures and compositions that are less sensitive to ther- mal fatigue, moreover, coatings also play a signicant role in reducing thermal fatigue eects, when milling. diametrically adjusted using the front and rear adjust- ing screws. e blade is micro-adjustable over a lim- ited range of radial movement and can be preset in a special-purpose setting xture (Fig. 141a and c), to ream the desired diameter that the tool can then con- sistently produce. is reaming blade normally has a back taper of: between 0.01 to 0.02 mm over a linear distance of between 10 to 25 mm, respectively – when positioned in the pre-setting xture (Fig. 141b shows a three-guide pad designed single-blade reamer). A fea- ture of the blade’s adjustment, is that it can be reset to compensate for any subsequent blade wear. A clamp, plus two clamping screws securely holds the blade in place, with the wedge-type clamp providing support along the entire blade length (Fig 74a). In the case of the single-bladed reamer design illustrated in Fig. 74a, the blade is located and positioned in the ream- ing head at an 12° positive rake angle. For this type of reamer design, additional standard blades can be t- ted, oering both 6° and 0° rake angles. Taper reaming setting can be achieved by mounting the taper reamer (i.e a taper reamer is shown ream- ing a component feature in Fig 73b), into the spe- cial-purpose setting xture (Fig. 141c). At least two dial-, or electronic-indicators are positioned along the blade’s length, then adjusted so that a very light pres- sure is applied to the cutting edge of the blade – to prevent it from inadvertently chipping. With the blade ‘semi-clamped’ , adjustment is made so that its is parallel along its length – relative to the tapered guide pads. Once the blade has been ‘fully clamped’ , adjustment occurs to position it higher than its guide pads’ diameter, by between 10 to 20 µm – all along the blade’s length, which achieves an accurate setting, but this setting will depend on both the workpiece mate- rial and the prevailing machining conditions 45 . .. Tool Store and its Presetting Facility – a Typical System In the worst case scenario, for many of the ‘old-style’ traditional workshops, the tools are as oen as not 45 Taper reamers – typical machining details: Cutting speed 4 to 20 m min –1 (Stainless steel 2 to 6 m min –1 ), Feed 0.2 to 0.8 mm rev –1 , Machining allowance 0.2 mm and up to 0.5 mm – for large taper reamers, plus Coolant soluble oil @ 10% dilution. Modular Tooling and Tool Management Figure 141. Presetting equipment and ‘guidelines’ for the setting of single-bladed reamers. Chapter treated with almost contempt, until they are required for a repeat order, or utilised for a new machining op- eration. Here, when the tools are not in use, problems arise because of the following: • Wasted and poorly utilised space – tools are kept either simply ‘oating around’ in an ‘ad hoc’ sys- tem, or are just sitting on top of each other – dam- aging the precision-ground tooling surfaces – while being kept in the open, • Time is lost looking for tools – due to the lack of any form of tool management, tools must be looked for located, then assembled – under less than ‘ideal con- ditions’ – so the minimum of tool control occurs, • Lack of eciency – as a result, more eort is re- quired by personnel who must try to nd tools, changing front- and back-ends to suit the selected machine tool for the production run causing lead- times to lengthen. Considering that up to 10% of the machine tool cost is tied-up in the purchase of tooling, then tools need to be looked aer with some degree of care and atten- tion. An area adjacent to the workshop, should be set aside for the purposes of storing tools and associated equipment in purpose-built tooling cabinets (Fig. 142) and form a basis for tool presetting activities. ere are several advantages in utilising telescoping drawer cabinets for tool storage (Fig. 137a and b), these in- clude: • Increased tool storage density – allowing the drawer space to be completely eciently lled-up in the minimum of space, • All tooling is kept under cover – thereby avoiding tool damage, while keeping tools dust and debris- free, • All tools and ‘associated paraphernalia’ are read- ily to hand – tooling drawers can be completely open-up, so that the contents are both easy to see and to arrange, • Tooling components t into their respective places – the drawers appropriately sectioned, to to- tally enclose the tools and their component parts, making it impossible for them to drop out and be damaged, • An organised and practical tool management sys- tem is achieved – within the tool store and pre- setting facility. erefore, all of the tooling com- ponents can be classied and categorised in the respective drawers – with every tooling part clearly seen. As a result of this ecient tooling component lay- out and tool-kitting facility, consumable tools can be ‘tracked’ within the tool store, but when these consum- ables leave the store vicinity (Fig. 142c), they are to all intents and purposes ‘scrapped’ as far as the tool stores are concerned. Returnable tools destined for eventual re-use can be ‘tracked’ around the machine shop by a number of tool-identication means (i.e as seen in Figs. 116 and 117 – using ‘tagged tools‘), or at the most basic of identication levels, by judicious labelling, or bar-coding of tools, with feed-back of information to the tool stores. Oen, for the most frequently used tools, they are assembled into a composite forms, then issued as ‘grouped-tools’ in the form of kits for a spe- cic job (i.e see Fig. 142c). Sometimes, tools are individually issued to ma- chine tool setters/operators and are not assembled into ‘kits’ , under such circumstances, the stores will keep a record to show: to whom they were issued, the machine tool on which they will be used, the num- ber and identication of these tools, together with the date of issue. A major benet of creating an area set-aside close to the machine tools for dedicated tool management, is that tool kits can be made-up ahead of the time – this being dictated by master schedule, so that they are ready just-in-time before any machining commences. A result of this timely tooling strategy, the lead times 46 are reduced, which is of prime importance to a com- pany in a competitive fast-developing market. Oen, it is the case that all tooling is assembled in the tool stores /preparation facility (Fig. 142b). is advanced preparation means that metrology-based 46 ‘Lead times’ , refer to the time taken before manufacture of the part, or prior to a production run beginning. ese ‘times’ are dependent upon a range of interrelated factors, such as: component stock quantities and their availability, the machine tools that are available, plus ‘line-balance’* factors, etc. *‘Line of balance’ (LOB), refers to a technique which permits the calculation of the quantities of the particular activities, or components which must have been completed by a particular intermediate date, in order that some nal delivery schedule might be satised. erefore, in this instance, it can be con- sidered as a machine tool scheduling and a control technique. In most of the LOB activities undertaken concerning machine tools, plant utilisation levels are paramount and if possible, a smooth and consistent LOB across all of the production ma- chines is desirable – for both high eciency and consistent work-throughput. Modular Tooling and Tool Management supplies such as ‘limit gauges’ 47 , together with jigs and xtures , are also the responsibility of the tool stores personnel, being despatched with the tool kits for a particular production run. When this is the case, to- tal packages are issued, containing: cutting-tool and work-holding kits, plus the limit gauges necessary for metrological checking/inspection. A tool store and prepartion facility with responsibility for all of these tooling-related aspects, becomes a ‘focal point’ for the machine shop for all matters relating to tooling, whether they are for breaking-down of previously used kits, calibration of gauges, or even purchase require- ments for the latest tool available. Specialist personnel in the tool stores/preparation facility, have consider- able responsibility in servicing tooling for the overall manufacturing resources on these machine tools and as a result, will have amassed a large working-know- ledge of the production tooling requirements, so their opinions should be sought prior to any purchasing de- cisions on new tooling. .. Computerised-Tool Management – a Practical Case for ‘Stand-alone’ Machine Tools If one considers the tooling requirement for a stand- alone machining centre, then today the market de- 47 ‘Limit gauges’ , are based upon the stated International Stan- dards agreed for ‘Limits and Fits’ for component toleranc- ing. e use of limit gauges, is a form of ‘attribute sampling’* where no attempt is made to determine the size of the work- piece toleranced feature, but they are simply utilised to estab- lish whether the component’s critical dimension is within the specied limits of size, or not. In practice, a component that has hole that has simply been drilled and reamed, might require a double-ended plug gauge, with one ‘Go’ end of the plug gauge being of full form and checking the maximum material con- dition and as many dimensions as possible, with the ‘Not go’ end checking the minimum material condition and only one dimension – which as its name implies, this latter end should not go into the reamed hole. is limit gauging technique ful- ls ‘Taylor’s eory of Gauging’. *‘Attribute sampling’ techniques, are a means of sampling im- perfections that are not in the strictest sense, measurable quan- tities. For example, a mirror-surface that has been produced, might be scratch-free, or may have other blemish marks, these factors might be cause for its rejection. Hence, ‘attribute sam- pling’ can be considered as a two-way classication system for either acceptance, or rejection of the workpiece. mands for its manufactured products has become much more diversied, with the number and multiplic- ity of tools required having also increased. As has been shown previously in this chapter in the preparation for workpiece machining, conrmation that all the tool- ing – including spares (i.e. ‘Sister-tooling’ – see Foot- note 1 in this chapter), must be loaded into the tool magazine. A computerised-tool management system (Fig. 143a), eliminates the possibility of mistakenly se- lecting the wrong tool and exacerbating the situation of placing it in the incorrect tooling pocket in the tool magazine. With these ‘tagged tools’ (Fig. 143d) having non-contacting read/write embedded microchips in say, the pull-stud region of the assembled tool – allow- ing coolant-through-spindle applications. e follow- ing tooling data can be automatically registered into the CNC memory (Fig. 143b), such as tool: number and its ID number; name and the nominal diameter; length, plus its ‘working-diameter’; thrust and power coecients; interference data, with ‘large diameter’ tool data – if required; life accumulated/actual usage time, wear and breakage ags. Many quite complex and sophisticated computer- ised-tool management systems exist, but essentially the practical system depicted in Fig. 143, can be use- fully applied to a machining centre in an ecient pro- duction environment. Here, the system comprises of three modules, these are: • Tool module – this being the smallest component of the tool management system, where the tooling data is both read/written at the machine magazine tool loading/unloading position (Fig. 143c). e tool data is automatically registered in the CNC memory at the push of a button, with this tooling- related data being continuously updated – as ma- chining continues, • Tool Management module – once this is combined with the ‘tool module’ (above), then tool manage- ment is conducted on a much larger scale, allowing not only all of the previous tooling data to be moni- tored and controlled, but additional information on the: toolholder’s bill of materials, insert inventory, and its location, together with a graphic tooling display of its build-up and information regarding the correct procedure to ensure fast and error-free tool measurement on the presetting machine (Fig. 143a), • Tool transportation module – consists of a tool transporter robot having high positional accuracy (i.e. not shown), which automatically transports Chapter Figure 142. An integrated tool and data management system – for complete tooling deployment. [Courtesy of Susta – Tool Handling] . Modular Tooling and Tool Management Figure 143. A computerised tool management system for an FMS facility. [Courtesy of Yamazaki Mazak]. Chapter the tools to-and-from each machine – changing the ‘stand-alone’ machine into a simple form of ex- ible manufacturing system (FMS). It consists of a ‘tool hive’ stocker, which acts to store tools in a cen- tralised and convenient location within the shop, having a tool tarnsport controller – controlling the overall system’s operation. Such tool management systems are becoming quite common-place in many highly-utilised manufacturing environments around the world of late, which consid- erably increases the overall utilisation rate of these au- tomated CNC machine tools. References Journals and Conference Papers Chandler, B. Crib Control [Organising Tooling Workplace]. Cutting Tool Eng’g., 48–53, Sept. 1999. Gough, J. 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