In machining aluminium alloys, here is what will help manufacturers reduce unit costs and achieve process reliability. Article by Walter AG.
A few years ago, chassis components made of aluminium were still reserved for the premium segment in the vehicle market. Steering knuckles, suspension arms and wheel carriers for medium-class and small cars were predominantly made of cast iron or forged steel. This has changed in the last few years.
Since then, significantly reducing the CO2 emissions of a vehicle has become a top priority in vehicle construction. One way to do this is reducing the vehicle weight. A reduction in weight of 100 kg means 0.3 l to 0.4 l less fuel consumption.
Even with electromobility as an alternative to the combustion engine, the weight of the vehicle is a key factor—the lighter the car, the higher the battery range. Materials like forged wrought aluminium alloys or ductile cast aluminium alloys with a low silicon content can therefore increasingly be found in all vehicle classes.
With the changeover to other materials, the challenges in machining also change. Machining aluminium alloys requires different machining strategies compared to existing materials in use, especially under the conditions of high cost pressure and strict machining quality and process reliability requirements. The machining tools used are an important factor here. Many automotive suppliers already count on machining specialist Walter AG for this.
“Aluminium alloys are the optimal material for the automotive industry. The alloys are light, with sufficiently high strength, and can be machined at speeds that are very different from those of traditional cast iron or steel materials. However, this does not mean that they are easy to machine. Above all, the long chips are a risk factor when it comes to a stable process. In addition, build-up on the cutting edge can quickly form on the cutting edges of the tools. It then soon becomes difficult to comply with the specified tolerances when it comes to the fit sizes and the surface quality. In this respect, users are dependent on the quality of the machining tool and the right technology,” says Fabian Hübner, Component and Project Manager for Transportation at Walter.
Above all, the integration of solid bores represents a technical and economic challenge in the production of chassis components made of aluminium alloys. While pre-forged recesses are often bored with larger bores, such as the wheel hub bore on the wheel carrier, smaller bores such as on the suspension arm are, in contrast, created in the solid material. The often high complexity of the contours to be drilled and the very strict requirements of the accuracy of the bore and of the surface quality also need to be considered.
Mostly, the smaller bores act as adaptors for plain bearings and dampers. This requires more than simply setting a bore. For example, defined end faces or chamfers must also be fitted, in order to allow you to fit bearing bushings or damping elements in the next production step. Consequently, up to five machining steps per bore quickly follow.
Check these articles out:
Sandvik Coromant Appoints New President
The Next Stage In The Evolution Of ISO Turning
Walter Tools Releases White Paper on Dynamic Milling
Silent Turning, Digitally Connected
For other exclusive articles, visit www.equipment-news.com.
WANT MORE INSIDER NEWS? SUBSCRIBE TO OUR DIGITAL MAGAZINE NOW!
FOLLOW US ON: LinkedIn, Facebook, Twitter
MAPAL is launching a new, particularly economical system of replaceable head reamers – the Press-to-Size-Reamer (PSR) – for customers who manufacture in large series. Thanks to the new development, the costs per bore are reduced massively.
The solid carbide replaceable heads are specifically adapted to individual diameters and geometries. The replaceable head system for the diameter range 10 to 25 mm consists of a robust holder, the solid carbide replaceable head and a coolant distribution element. The connection is highly accurate. This means that the heads can be changed by the customer’s employee on site without any adjustment or logistics effort, a big plus in terms of cost-effectiveness. The replaceable head is merely exchanged and disposed of. There is no provision for reconditioning the replaceable heads.
By eliminating the logistics cycle, the new replaceable head system significantly improves the economic efficiency of reaming operations in large-scale production. This effect is even reinforced by the fact that, in contrast to carbide-tipped reaming tools, the solid carbide replaceable heads can be designed with a CVD coating – with correspondingly positive effects on tool life.
Check these articles out:
Big Kaiser: EWE Digital Boring Head
Delivering Singapore’s Logistics Industry Into The Digital Era
Tenova Deploys ABB Automation And Drives Systems For New Tinning Line Plant In Southeast Asia
ABB To Supply Complete Electrical And Automation System For China’s Northern Copper Industry
For other exclusive articles, visit www.equipment-news.com.
WANT MORE INSIDER NEWS? SUBSCRIBE TO OUR DIGITAL MAGAZINE NOW!
FOLLOW US ON: LinkedIn, Facebook, Twitter
Tom Nathan of ANCA explains how demand for carbon fibre reinforced plastics (CFRP) growing at 9.3 percent per year leads to huge potential for cutting tool manufacturers.
Using strengthening fibres embedded in a supporting material has been around since the dawn of time. From mud brick houses reinforced with straw to the first composite bows made with wood, bone and pine resin, it was recognised that composites deliver superior compressive and tensile properties.
The transportation, low-carbon energy generation, aerospace, defence, civil construction and sporting goods industries have all adopted composites for their high-performance and low weight applications—and the demand continues to grow year-on-year. A report by Credence Research in 2019 estimates a Compound Annual Growth Rate (CAGR) of 9.3% for Carbon Fibre Reinforced Plastics (CFRP) during the period 2017-2025. Growth in the poly-crystalline diamond (PCD) tool market has been double that of standard carbide cutting tools over recent years, making it an outstanding opportunity for tool manufacturers looking to be active at the leading edge of cutting tool technology.
Tom Nathan, product manager at ANCA, has witnessed the huge increase in inquiries in this area – reflecting a growing demand by tool manufacturers to produce cutting tools to service this market. “Commercial applications for composite materials continues to grow year-on-year with the market space for cutting tools also expanding. With superior strength to weight ratios, CFRP is being used in a wide variety of low weight structural applications from planes, cars, turbines and even drones,” he says.
Cutting tool manufacturers are creating and adopting a variety of cutting tool designs and technologies—developing new tooling for the wide variety of composites used today. ANCA has been working closely with its customers to design innovative solutions that help address these needs, creating new tool geometries and machine technologies that can erode and grind market-leading CFRP solutions.
Industries today use a variety of composite-matrix materials (epoxies, phenolics, polyimides) and fibres (carbon, Kevlar, glass) to suit varying applications with very different material properties. In metal cutting, the creation and evacuation of chips serve to remove heat from the point of cutting. In a polymer matrix composite, the matrix tends to be soft but very tough. When analysed at the micro level, machining of polymer matrices does not form chips, but rather a fine ‘dust’ that results from localised micro-fracturing. This matrix dust does not readily dissipate heat from the cutting edge as the matrix material generally has a very low thermal conductivity.
Nathan states that this creates significant problems when using ferrous (iron) based cutting tools for machining composites. “The increased heat leads to localised thermal expansion and lower yield strength which varies the tool geometry, ultimately leading to premature wear,” he says.
The next challenge comes from the embedded fibres. These fibres are strong, stiff and highly abrasive when machined. Different composite materials utilise different fibre orientation methods to aid the mechanical properties sought. Fibre forms can be unidirectional, fabric weaves, braided or even chopped which makes the composite materials behave very differently when being machined.
To complicate matters more, Carbon Fibre Reinforced Plastics (CFRP) can be layered with backing materials comprised of aluminium or titanium to aid strength and rigidity. Alone, these substrates require their own types of tooling geometries, however, varying layers of these materials with matrix composites materials demands tool geometries that can cater for a wide variety of machining operations with dramatically different cutting properties.
For other exclusive articles, visit www.equipment-news.com.
Check these articles out:
Guhring Philippines Discusses Metal-Cutting Tool Landscape And Outlook
COVID-19 Impact On Global Machine Tool Market
Schunk Launches Manually Actuated Clamping Module
Dormer Pramet Strengthens Asia Capabilities With Acquisition Of Miranda Tools
LVD Launches New Large-Format Laser Cutting Machine
Kennametal Launches 3D Printing Business Unit
WANT MORE INSIDER NEWS? SUBSCRIBE TO OUR DIGITAL MAGAZINE NOW!
FOLLOW US ON: LinkedIn, Facebook, Twitter
Seco Tools has completed the acquisition of the cutting tool division of Quimmco Centro Tecnológico (QCT), a subsidiary of the Quimmco Group. The cutting tool division acquired from QCT has three locations in Mexico to support customers and is a leading solid carbide tooling manufacturer, specializing in custom products and reconditioning.
“With this acquisition we build an even stronger foundation in North America for our round tools business. Giving us additional capabilities within the fast-growing area of round tools,” says Fredrik Vejgården, President of Seco Tools, AB.
The cutting tool division acquired from QCT will continue to serve its present customers and begin serving Seco customers directly after closing. As of June 1, they have become a wholly owned part of Seco Tools Mexico and will discontinue use of the QCT name.
“This is a great complement to our product and service portfolio in North America and enables Seco to serve the growing demand for solid carbide tools in Mexico,” says Rob Keenan, President, Seco North America. “The demand for high performance tooling solutions in Mexico is increasing, especially in the aerospace and automotive segments and the QCT acquisition positions us to meet that demand by being close to customers with engineering and production capabilities.”
For other exclusive articles, visit www.equipment-news.com.
Check these articles out:
Seco Tools: Prevent Delamination In Hybrid Stacked Material Machining
Seco Tools Releases New Duratomic TM Grades for Stainless Steel Turning
Are Cheaper CNC Machine Tools More Cost Effective?
Predictive Maintenance Solutions For Machine Tools Reduce Cost The Smart Way
NUM Launches Active Vibration Control System For CNC Machine Tools
Not A Small Challenge: Cutting Tools for Miniature Dental and Medical Parts
WANT MORE INSIDER NEWS? SUBSCRIBE TO OUR DIGITAL MAGAZINE NOW!
FOLLOW US ON: LinkedIn, Facebook, Twitter
How to say no to vibrations in machining? Find out more in this article by Andrei Petrilin, Technical Manager at ISCAR.
Figure 2: The FINISHRED series of solid carbide endmills features chip-splitting geometry coupled with variable pitch flutes.
Vibrations in machining are generally an unavoidable part of the metal cutting process. They have a forced or self-excited nature and always accompany a cutting action. Machining vibrations are referred to as “chatter,” highlighting their specific nature, which inheres in every processing where chips are formed. Even if cutting is considered as stable, it does not mean that vibrations do not take place. In this case, the vibrations simply remain on a level that provides the required machining results, and is considered as a “no vibration” operation.
READ: Machining for the Aerospace Industry
In fact, vibrations in cutting are a damaging factor that reduces performance. Manufacturers make every effort to diminish vibration and, ideally, bring them to a level that does not affect machining results. Chatter is a subject of serious research that has already provided manufacturers with ways to model vibrations in machining which, despite their complexity, can be very effective in finding a way to reduce chatter. However, this modelling takes time and requires various input data, including sometimes additional measurements. In most cases, when manufacturers face vibrations during machining, they only have a few tools at their disposal for a real-time response to decrease the chatter. The most common practice is to vary cutting speed and feed, which usually leads to productivity reduction. Therefore, any effective method of diminishing vibrations that does not adversely affect machining operation productivity will be attractive to manufacturers.
Vibration reduction in machining requires consideration of a manufacturing unit as a system comprising the following interrelated elements: a machine, a workpiece, a work-holding device, and a cutting tool. While the influence of each element on total vibration reduction is different, improving a vibration characteristic of one element may have a significant impact on the system’s overall dynamic behaviour. Most efforts to protect against vibrations focus on developing more rigid machines with intelligent sensors and computer control, and advanced vibration-dampening tooling. Can a cutting tool, the smallest – and probably the simplest – system component, dramatically change the vibration strength of a manufacturing unit? Even though producers might not have great hopes for the role of cutting tools in decreasing chatter, in certain cases a correctly selected tool can simply stop vibration without any adverse effect on productivity.
Figure 3: The SUMOCHAM-IQ family of HCP exchangeable carbide heads.
The right tool geometry makes cutting action smooth and stable. The geometry strongly influences cutting force fluctuations, chip evacuation and other factors, which are connected directly with vibration modes. ISCAR’s tool design engineers believe that the cutting geometry can considerably strengthen vibration dampening of a tool and have developed interesting solutions accordingly.
READ: Five Stars for Effective Chamfering
ISCAR’s various indexable inserts, exchangeable heads, and solid carbide tools feature chip-splitting cutting edges. Such an edge may be serrated or have chip-splitting grooves. The chip splitting action causes a wide chip to be divided into small segments, resulting in better dynamic behaviour of a tool during machining, and vibration is stabilised. In rough machining, extended flute milling cutters remove a large material stock and work in heavy conditions. Significant cutting forces acting cyclically generate vibration problems. When using chip-splitting indexable inserts, it is possible to tackle these difficulties. Mills with round inserts, a real workhorse in machining cavities and pockets, particularly in die and mold making, are often operated at high overhang that affects rigidity and vibration resistance of a tool. Problems with cutting stability occur when the overhang already exceeds 3 tool diameters. Applying serrated round inserts with a chip-splitting effect redresses this situation and substantially improves robustness (Figure 1).
A skilfully defined tooth pitch is an effective way of taking the dynamic behaviour of a cutting tool to the next level. ISCAR’s CHATTERFREE family of solid carbide endmills (SCEM) was designed on the basis of a pitch control method. The family features a variable angle pitch in combination with a different helix angle. This concept ensures chatter free milling in a broad range of applications.
The FINISHRED series of solid carbide endmills features chip-splitting geometry coupled with variable pitch flutes (Figure 2) that provide surface finish when machined according to rough machining data.
The principles of vibration-proof cutting geometry, which demonstrated their effectiveness in solid carbide endmills , have been applied to the design of exchangeable multi-flute milling heads made from cemented carbides in the MULTI-MASTER family.
Figure 4: ISCAR’s ISOTURN WHISPERLINE family of anti-vibration cylindrical bars.
Chatter in drilling leads to poor surface finish and accuracy problems. In ISCAR’s SUMOCHAM family of assembled drills with exchangeable carbide heads, the double margin design of QCP/ICP-2M heads substantially increases tool dynamic stability.
READ: Iscar F3S Chipformer For Finish Turning On Superalloys And Exotic Materials
If vibration occurs when a drill enters material, it may cause serious damage and even breakage of the drill. The SUMOCHAM-IQ family of HCP exchangeable carbide heads (Figure 3), intended for mounting in the bodies of standard SUMOCHAM tools, can ensure reliable self-centring capabilities. The key is an unusual concave profile for the head cutting edge reminiscent of a pagoda shape. This original cutting geometry enables high-quality drilling holes of depths of up to twelve hole diameters, directly into solid material without pre-drilling a pilot hole.
The “magic pagoda” features another ISCAR innovation: the LOGIQ3CHAM family of latest-generation drills carrying exchangeable carbide heads with 3 teeth to ensure higher productivity. The steel drill bodies have 3 helical flute that weaken the body structure when compared with a 2-flute assembled drill of the same diameter. In order to improve the dynamic rigidity, the flute helix angle is variable. This design principle in combination with the pagoda-shaped cutting edge provides a durable chatter-proof solution for stable high-efficiency drilling.
An assembled cutting tool comprises a body with mounted cutting elements such as indexable inserts or exchangeable heads. Choosing the right body material presents an additional option for forming a chatter-free tool structure. Most tool bodies are made from high-quality tool steel grades, for which the material stress-strain behavior is similar. However, in some cases tool design engineers have identified successful material alternatives to improve vibration strength.
READ: ISCAR CTO Stresses On Productivity Improvement
The MULTI-MASTER, an ISCAR family of rotating tools with exchangeable heads, provides a range of tool bodies, referred to as shanks, produced from steel, tungsten carbide or heavy metal. A steel shank is the most versatile. Tungsten carbide with its substantial Young’s modulus provides an extremely rigid design, so carbide shanks are used mainly when milling at high overhang and machining internal circumferential grooves. Heavy metal, an alloy containing around 90 percent tungsten, is characterised by its vibration-absorbing properties, and heavy metal shanks are most advantageous for light to medium cutting operations in unstable conditions.
A typical tool for internal turning or boring operations comprises a boring bar with a mounted insert or a cartridge carrying an insert. The bar is the main factor in the dynamic behaviour of a tool. Stiffness of a bar is the function of the bar overhang to diameter ratio, and large ratios may be a reason of tool deflection and vibrations, affecting dimensional accuracy and surface finish during machining.
ISCAR has developed three types of boring bar to cover a wide range of boring applications: two integral (from steel and solid carbide) and one assembled, having a vibration dampening system inside.
READ: Limitless Shoulder Grooving
The steel bars enable stable machining with the overhang up to four diameters. Exceeding this value can induce vibrations due to steel’s elasticity characteristics. Changing the bar material from steel to a more rigid solid carbide ensures efficient vibration-free boring with the overhang of up to seven diameters. However, further increasing the boring depth is also limited by the material stress-strain behaviour. In order to clear this overhang barrier, ISCAR developed the ISOTURN WHISPERLINE family of anti-vibration cylindrical bars. The bars carry interchangeable boring heads for indexable inserts of different geometries and have inner coolant supply capability. The main element of the bar design is a built-in vibration-dampening mechanism to provide “live” vibration damping during machining. This enables effective boring with the overhang from seven to 14 diameters (Figure 4).
A vibration-dampening unit is used also in ISCAR deep grooving and parting tools. The unit is in a tool blade under the insert pocket. Each blade is pre-calibrated by ISCAR for optimal performance for a wide range of overhangs, but end-users can complete fine tuning calibration themselves if needed.
Cutting tool manufacturers have a limited choice of means in the abatement of machining vibrations, with only tool cutting geometry, tool body material, and maybe a cutting tool with built-in vibration-damping device at their disposition. Considerable skill and ingenuity are required to make a chatter-free tool with these limited resources. It is feasible, however, and ISCAR’s solutions highlighted in the above examples affirm the possibilities.
For other exclusive articles, visit www.equipment-news.com.
Check these articles out:
Kennametal KOR 5: The King Of Roughing
Not A Small Challenge: Cutting Tools for Miniature Dental and Medical Parts
WALTER: New Eroding And Grinding Machine With The Well-Known “Two-In-One” Concept
The Metal Machining Versatility of Abrasive Waterjets
Igus Expands 3D Printing Service By Injection Moulding With Printed Tools
c-Com Projects With MARPOSS And Oerlikon Balzers To Introduce Intelligent App For Tooling
The Next Stage In The Evolution Of ISO Turning
Walter: Vibration-Free Machining In Difficult Conditions
WANT MORE INSIDER NEWS? SUBSCRIBE TO OUR DIGITAL MAGAZINE NOW!
FOLLOW US ON: LinkedIn, Facebook, Twitter
Successful development of innovative and dynamic parts in today’s miniature dental and medical components industry presents a formidable and equally dynamic challenge to cutting tool manufacturers. Article by ISCAR.
Successful development of innovative and dynamic parts in today’s miniature dental and medical components industry presents a formidable and equally dynamic challenge to cutting tool manufacturers.
The fast-growing field is driven by enterprising orthopaedic surgeons and dental professionals together with medical screw and implant companies, who work in close cooperation with computer aided design and manufacturing (CAD/CAM) software developers and dedicated machine and tool manufacturers to transform their inventions into parts that are revolutionizing medical and dental procedures. Each new component demands correspondingly advanced tools and geometries to create the new and complex shapes, and to ensure extreme precision and consistently excellent surfaces.
The materials used for producing medical screws and implants are titanium superalloys, although stainless steel hard materials are used when a special ratio of depth of cut to chip thickness is required. These materials are gummy and cause built-up edge (BUE), which tends to wear down edge sharpness, while the high temperatures generated during chip breaking shorten tool life and damage surface quality.
ISCAR, a manufacturer of cutting tools for metalworking, invested time and resources to develop optimal machining solutions for the medical sector, applying unique geometries, tools, and grades. Utilizing CAD/CAM systems to create custom tool assemblies according to the ISO 13399 standard, ISCAR developed cutting tools for machining miniature medical parts—specifically dental screws and four components for hip joint replacement implants: femoral head, acetabular shell, femoral stem, and bone plate.
ISCAR provides dedicated cutting tools for each of the main operations involved in machining dental screws. The company developed two options for rough OD (outer dimension) turning. The SwissCut compact tool is designed for Swiss-type automatics and CNC lathes, and enables reduced setup time and easy indexing without having to remove the toolholder from the machine, while the inserts are equipped with chip deflectors designed specifically for machining small parts. The second option features SwissTurn toolholders, with a unique clamping mechanism to optimize insert clamping and replacement on Swiss-type machines, and JETCUT high pressure coolant tools. SwissCut tools are used for the turn threading operation.
CHATTERFREE endmills are utilized for the slot milling stage to maximize stock removal rate, eliminate vibration and reduce cycle time. The unique ground geometry provides excellent surface and tool life, while machining at high material removal rates.
PENTACUT parting and grooving inserts perform the cut-off operations. With five cutting edges and very rigid insert clamping, PENTACUT is a stronger insert for higher machining parameters particularly on soft materials, parting of tubes, small and thin-walled parts.
SwissCut tools are used in the face and OD turning (screw head turning) operation, while the drilling operation is performed by SOLIDDRILL solid carbide drills with 3xD and 5xD drilling depths and right-hand cut. The drills feature coolant holes.
The thread milling operation features SOLIDTHREAD thread mills, whose short three-tooth cutting zone with three flutes and released neck between the cutting zone and the shank enable precise profiles and high performance. The extremely short profile exerts a low force which minimizes tool bending, facilitating parallel and high thread precision for the entire length. The solid carbide SolidMill endmills perform the key head milling operation.
Complex operations are involved in machining components for hip joint replacement, which demand high accuracy, pristine surface quality, and absolute reliability. ISCAR provides products for each operation to maximize their precision and efficiency.
Femoral Head
The machining required for a femoral head involves rough turning or rough grooving, semi-finish profile turning, rough drilling, semi-finish milling, semi-finish internal turning, internal grooving (undercut), cut-off, rough turning, and semi-finish turning.
The ISOTURN turning tools may be used for rough turning. The ISO standard tools perform most of the industry’s chip removal in applications ranging from finishing to roughing. Offered in all standard geometries, the trigon (semi-triangular) turning inserts for axial and face turning features six 80° corner cutting edges. For profile machining, ISCAR provides intricate and precise V-LOCK V-shaped special profile grooving inserts for the range of 10–36mm.
SUMOCHAM drilling tools perform the rough drilling operation, offering fast metal removal and economical indexing with no setup time. SUMOCHAM integrates a clamping system that enables improved productivity output rates and a shank designed with twisted nozzles, and a durable and stable body.
The CHATTERFREE 4-flute endmills are utilized for the semi-finish milling operation. CHAMGROOVE internal grooving inserts are applied for semi-finish grooving. The inserts possess extremely small bore diameters starting at just 8mm and incorporate internal coolant.
Semi-finish internal turning is performed by ISOTURN inserts with SWISSTURN toolholders, while the cut-off operation uses DO-GRIP twisted double-sided parting inserts which feature double-ended twisted geometry for no depth of cut limitation.
For rough turning, the SWISSTURN ISO standard insert range with small shank sizes is used. Also available for this operation are standard geometry inserts with precision ground cutting-edges and small radii for manufacturing small and thin parts. The semi-finish turning operation is performed by using CUT-GRIP inserts.
Acetabular Shell
Machining of the acetabular shell component consists of rough internal turning, finish profile milling, shouldering, upper and bottom chamfering, drilling, thread milling, external rough turning, and external grooving operations.
HELI-GRIP double-ended inserts are used for the rough internal turning operation, as the twisted design allows them to groove deeper than the insert length. Internal finish milling is performed by SolidMill 3-flute, 30 deg helix short solid carbide ball nose endmills. SolidMill endmills with 4 flutes, 38° helix perform the finish shouldering operations, as well as the special-shaped endmill which performs the upper and bottom chamfering operations that follow the drilling stage. The SOLIDDRILL solid carbide drills are used for the drilling operation.
Thread milling is performed by SolidMill solid carbide internal threading endmills, which integrate coolant holes for ISO thread profiles. ISO standard inserts with SwissTurn toolholders are used for rough turning, and external grooving is performed with CUT-GRIP precision inserts.
SolidMill endmills with four flutes, 38° helix and SolidMill three flute, 30° helix short solid carbide ball nose endmills perform the final milling operations.
Femoral Stem
Machining the femoral stem involves slotting, spot milling, drilling, chamfer milling, turning, face and profile milling operations.
MULTI-MASTER endmills with indexable solid carbide heads in the diameter range of 12.7–25mm are used for the slotting operation. Spot milling is performed by means of SolidMill endmills with four flutes, 38° helix and variable pitch for chatter dampening with 3xD relieved necks. The drilling operation uses SOLIDDRILL solid carbide drills, while chamfer milling is performed using MULTI-MASTER endmills with indexable solid carbide heads. ISO standard geometry inserts with precision ground cutting edges are used with SWISSTURN toolholders for the turning operation.
SolidMill three-flute, 30 deg helix short solid carbide ball nose endmills are employed for the profile milling operation, and SolidMill endmills with four flutes, 38 deg helix and variable pitch for chatter dampening with 3xD relieved necks are utilized for face milling.
Bone Plate
The machining required to manufacture a bone plate involves rough and finish milling, shouldering, drilling, and mill threading. For rough milling, the FINISHRED endmill geometries allow the tool to perform roughing and finishing operations at the same time. The result is the ability to apply roughing machining conditions, while obtaining excellent surface finish. MULTI-MASTER interchangeable solid carbide tapered heads are applied to the finish milling operation, whereby the curved surfaces can be machined by tilting the tool and applying a large corner radius at small cutting depths. Shouldering is performed with CHATTERFREE endmills, which enable high material removal rates, eliminate vibration, and reduce cycle time.
For the final milling stage, MULTI-MASTER four flute, 30 deg helix short solid carbide ball nose endmills in the 5–25mm range are employed, while SOLIDDRILL solid carbide drills are used to ensure stable and accurate drilling. SOLIDTHREAD 55 deg or 60 deg profile solid carbide taper thread mills are used for the mill threading operation.
Grades specifically designed for machining applications on stainless steel and super alloys such as IC900, IC907, IC806, IC908, IC328, and IC928 are ideal for milling and turning titanium and nickel-based alloys, such as Nitinol, commonly found in medical components. These grades are available for ISCAR standard tools with specially designed positive and sharp edged chipformers.
It is no small challenge to manufacture miniature parts for dental and medical devices but ISCAR has succeeded in developing highly effective cutting tools for this field that adhere to the stringent standards of quality and precision essential for medical industry applications.
WANT MORE INSIDER NEWS? SUBSCRIBE TO OUR DIGITAL MAGAZINE NOW!
FOLLOW US ON: LinkedIn, Facebook, Twitter
In principle, machining large parts involves the same cutting action and chip formation process as for small or mid-size parts. However, large dimensions demand a specific approach to machining, and manufacturers need to plan technological processes and choose more effective cutting tools in order to produce heavy parts that take up a great deal of space. Article by Andrei Petrilin, Technical Manager, ISCAR.
Transporting a part inside a shop floor, mounting the part in a machine tool and clamping it properly, and machine setup are major challenges. Workholding massive and large parts is not an easy task, and often requires non-standard solutions. Machining large parts involves removing a lot of material that may cause significant deformations due to unrelieved stresses. Another factor, which leads to dimensional problems, is thermal expansion caused by heat generation during cutting: the large sizes make it much more sensitive comparing with “normal-in-size” workpieces. The necessity to remove a significant material stock requires appropriate chip evacuation to prevent the chip re-cutting, which negatively affects the applied cutting tools.
The key for overcoming the difficulties lies in technology, based on effective process planning and utilizing the most suitable machine tools, optimal workholding, and minimal part relocation. Single setup machining represents an absolute ideal for machining a large part, and producers from fields such as power generation, aerospace , railway, die and mold making, and heavy industry make every effort to approach this ideal. And cutting tools play a meaningful role towards reaching the target.
A distinct feature of these industries is their substantial consumption of large heavy-duty tools, mostly indexable, intended for productive removal of large quantities of material, especially in rough and semi-rough machining operations.
Large part manufacturers expect the same from cutting tools as any other producer using metal cutting technologies: excellent performance, good tool life, and high reliability. The latter two are especially essential because the large sizes lead to increased machining time, but replacing a worn tool in the middle of a pass and unpredictable breakage of the tool during cutting are totally unacceptable. In order to maximally meet the requirements of large part manufacturers, cutting tool producers provide various solutions, based on both standard and special designs. As a leading company in the cutting tool industry, ISCAR’s years of accumulated knowhow and experience have proved to be advantageous in developing efficient solutions to these challenges.
Figure 1
It is hard to machine a large part without face milling operations. Rough and fine machining of free and bounded planes and preparing datum surfaces require various indexable face mills. ISCAR’s standard face mills possess nominal diameters up to 315 mm (12″), while special tailor-made tools might feature higher values. The inserts are mounted in face mills and vary in cutting geometry as they are intended for machining different groups of material. Significant removal of machining stock by milling is primarily an issue for the production of large parts from steel and cast iron and, slightly less, from titanium and aluminum.
ISCAR’s line of standard face mills includes many tool families for large part manufacturing. HELITANG T465 features cutters with a 65° cutting edge angle and carrying tangentially clamped inserts. The robust design enables productive machining with a depth of cut up to 19 mm (.750″). The HELIDO 890 family features 89° face mills with lay-down square double-sided inserts (Fig. 1). These efficient mills, which are truly indispensable in milling a plane near the shoulder, offer an important economic advantage: the square inserts provide eight indexable cutting edges for depth of cut up to 9 mm (.354″).
Indexable extended flute “long-edge” cutters are considered as winning tools for productive rough milling. In manufacturing large parts, they excel in machining deep shoulders and cavities. Extended flute cutters are also utilised in “edging” – milling wide straight edges, an operation which is common for various processes from machining slabs and ingots to primary contouring.
Figure 2
ISCAR’s line of indexable extended flute cutters varies in design configuration, integrating a shank- and arbour-type mounting method and a radial or tangential insert clamping principle. These tools work in hard cutting conditions and experience significant mechanical and thermal loading. Intensive material removal requires the appropriate volume of a tool chip gullet to ensure effective chip evacuation. The situation can be dramatically improved by applying ISCAR’s extended flute cutters carrying inserts with chip splitting geometry to divide a wide chip into small segments. As a result, cutting forces are reduced, vibrations are stabilized, and thermal problems are eased.
Although 90° tools are the most commonly used cutters, machining large parts also requires rough milling of inclined and 3D surfaces, for which ISCAR provides a family of tapered extended flute cutters with 22.5°- 75°cutting edge angles. In some cases, particularly in die and mold making, combined rough and shoulder milling is needed. The DROPMILL 3 extended flute ball nose mills were designed specifically for such applications.
Producing large-size aerospace components from hard-to-machine titanium alloys is an extremely metal-intensive process with a significant buy-to-fly ratio. The eventual weight of a part may be only 10%, or even less, of the original weight of a workpiece. The XQUAD extended flute cutter family, one of ISCAR’s newest products, is intended for high-efficiency milling of deep cavities and wide edges in titanium parts. These tools (Fig. 2) are suitable for machining with high pressure coolant supply, which significantly increases productivity and improves tool life. The tools have already proved themselves: for example, component producers have achieved a 700-1000 cm³/min (43-61 in³/min) metal removal rate (MRR) by using an 80 mm (3”) diameter XQUAD cutter.
In railway engineering, combine mills are used to ensure simultaneous machining on several areas of the part. These mills incorporate an extended cutting edge, formed by a set of successively mounted indexable inserts.
Figure 3
High efficiency machining by indexable extended flute cutters and large-diameter face mills can be likened to the work of a heavy excavator digging sand with a big bucket. The full sand bucket, operated by a powerful engine, slowly moves a large volume of waste material. At the same time, there is an alternative method for efficient excavating. Imagine a more compact track trencher with a rapidly moving digging chain. Each link of the chain removes a small volume of sand but does it fast. In metal cutting, this trencher is a high feed mill, which machines at shallow depths of cut but with a feed per tooth that is far higher than the usual rates – millimetres as opposed to tenths of millimetres.
Fast feed mills are applied mainly to rough machining of plane faces, cavities and 3D surfaces (Fig. 3). These tools are more typical in manufacturing large parts from steel and cast iron, although high feed milling (HFM) titanium and high temperature alloys is not uncommon today.
ISCAR has a wide choice of fast feed mill families, intended for cutting various materials in different applications. The “world” of ISCAR’s HFM cutters encompasses tool families in diameter ranges of up to 160 mm (6.3″) that can meet the requirements of the most demanding customer.
High feed milling requires machine tools with high-speed feed drive. Large part manufacturers often have heavy, powerful but slow machines that are not suitable for high feed face milling. For these customers, ISCAR developed moderate feed (MF) cutters. Compared with fast feed mills, moderate feed cutters feature a higher cutting edge angle; they move slower but machine at higher depths and need more power to make them suitable for applying to heavy machines.
Large parts are often made from difficult-to-cut materials such as hard and high wear-resistant steel or cast iron. The welded part structure and the process of repairing worn parts by spraying fillers or soldering, add materials that are not easy-to-machine either. High speed milling (HSM) resolves these issues. Originally applied in die and mold making, high speed milling was developed as a productive method of milling hard steel that led to decreasing a part relocation, lessening setup, minimizing manual finish and polish, and, as a result, reducing cycle time. High speed milling features a small-in-diameter tool that rotates at high speed and mills material at shallow, light cuts.
The most suitable HSM tool is a solid carbide endmill and ISCAR’s MULTI-MASTER family of assembled endmills, which carry cemented carbide exchangeable heads, also represents a viable option. ISCAR’s line of solid carbide endmills offers various multi-flute tools in diameters of up to 20 mm (.750″), intended for high speed milling materials with hardness up to HRC 70. Decreasing machining allowances due to the production of more accurate workpieces for large parts, for example by using precise casting or molding, opens up new opportunities for high speed milling.
Figure 4
In many cases, manufacturing large parts is small-volume and even individual. In this context, minimizing machine tool downtime has critical importance. Intelligent process planning to considerably reduce setup time can help solve this issue. Each time a worn cutter is replaced, additional measuring and CNC program corrections are required, which increases downtime.
ISCAR’s families of rotating assembled tools with exchangeable heads – MULTI-MASTER mills and SUMOCHAM drills (Fig. 4) – enable substantial decreases in downtime. Face contact between a head and a tool body ensures that the head overhang is within strict tolerance limits, resulting in high dimensional repeatability of the assembly. Replacing a worn head does not require additional setup operations or removal of the tool from a machine.
Figure 5
Turn milling, which is the method of cutting a rotating workpiece by a face milling cutter, is a good option for machining heavy rotary parts. In turning, the cutting speed is a function of rotating velocity. If the main drive of a machine tool does not allow rotation of large masses with the required velocity, due to limitations of its working characteristics, then the cutting speed is far from the optimal range and turning performance will be low. Turn milling offers an effective solution to the above difficulties. When turning large eccentric parts like crankshafts, off-centre masses of the parts cause unbalanced forces that adversely affect performance. Turn milling features low rotary velocity of a part, which prevents this negative effect (Fig. 5).
The majority of ISCAR’s indexable face-milling cutters are suitable for turn milling. The success of their application depends on cutter positioning with respect to the machined part, choosing optimal geometry of inserts, and cutting data calculation. ISCAR’s specialists in the field studied turn-milling kinematics and developed an appropriate methodology for defining these parameters.
Machining large parts is a time-consuming process, during which the tools cut material for a long period, and this means that tool reliability, stability, and predictable wear are high priority issues. A sudden tool failure may seriously damage the part and even cause its rejection. A cutting tool manufacturer has a limited choice of instruments for improving reliability, including advanced tool design, progressive cutting material, and technological development. Effective utilization of these instruments is the key to successful large part machining and ISCAR’s recently-introduced range of new tools and carbide grades provides that key.
FOLLOW US ON: LinkedIn, Facebook, Twitter
READ MORE IN OUR LATEST ISSUE!
WANT MORE INSIDER NEWS? SUBSCRIBE TO OUR DIGITAL MAGAZINE NOW!
