How to enhance CNC utilisation thereby productivity

February 12, 2016 5:30 pm

Experts from the industry speak on enhancing CNC utilisation thereby productivity and the latest products in CNC
  There are various ways of enhancing productivity in a CNC machine, thereby improving the overall utilisation of the machine – reducing set-up time, positive ergonomics and increasing cutting parameters.
“We generally ignore to reduce the set-up time, though much can be achieved through it. Also, as manufacturers of cutting tools, we focus on improving productivity by increasing parameters. For this we develop new geometries which break the chips effectively into small pieces so that most of the heat generated during machining is carried away by the chip. We also develop new grades, which can withstand high hot hardness, thereby facilitating higher cutting speeds, and thereby increasing productivity,” says Gautam K Ahuja, Managing Director, Dormer Tools India Pvt Ltd.
Keshav Khurana, Executive Director, Wohlhaupter India Pvt Ltd feels, “For the best utilisation of CNC machines, planning is the key. Shopfloor process flow, providing material and machining inputs to the machines in efficient ways can improve the utilisation and thereby productivity to begin with. Following the correct workflow/ process flow suiting the component can result in desirable results. Then comes the role of efficient machines and tools, reducing the cycle time. Capable machines as per component, suitable tools greatly help in productivity improvement.”
In todays’ era, manufacturers are constantly thriving to increase productivity, performance and profit while lowering costs. CNC technology helps them accomplish this by increasing throughput.“TCO (Total cost of ownership) and MTBF (Mean time between failure) helps you get a better understanding of uptime, machine utilisation and cost per part. In ‘just-in-time’ manufacturing environment, CNC’s reliability, efficiency and advancements can help to reduce cycle time and thereby also reduce the overall cost per part,” states Nitesh Gupta, GM – Product and Business Development, Haas Automation.
When purchasing a new machine tool it is easy to focus solely on the capital cost of the equipment, without taking into account the recurring costs necessary to run and maintain the machine.
Manufacturers are being constantly challenged to increase productivity while lowering costs, like developments in the personal computing industry, the rate of CNC advancement also has accelerated. Similarly, it is no longer acceptable for a CNC manufacturer to have a computing platform linger for a decade or more.
“CNC machines are mother machine in any industry. Since CNC machines come in existence quality and productivity enhance many times. Production CNC are smarter and faster now days while dies and mould CNC are more precision and advance,” says Rajesh Kushwaha, MD, Multi axis CNC-Gurgaon.
Increased use of CNC machines or CNC automation doesn’t result in enhanced productivity directly. Systematic training in manufacturing practices is highly crucial and well trained manpower can bring in significant improvement in productivity and quality levels thereby increased profitability. Amidst the competitive work environment today, effective utilisation of resources including CNC machines, tooling, work holding and other accessories is the key to realise ever growing need for higher productivity.
As per Kushwaha, while using CNC machines in dies and moulds and enhance the productivity, following things must be considered:• Machine foundation• Machine rigidity• Spindle power• Work holding device• Cooling device• Tool holding device• Tool selection• Run out (tool holder or spindle)• CAM programming• Parameter selection• Data transfer or DNC• Skilled operator.
Reducing cycle timeUsing the latest CNC technology that integrates a high-speed CNC with drive system hardware containing servo and spindle motors featuring ultrasmooth rotation, accurate current detection, and high-resolution feedback devices helps to reduce cycle time.
Bell-shaped acceleration or deceleration minimises machine shock and reduces movement time. This can be applied to rapid, contouring, and tapping motions.Some other functions that can affect cycle time are:• Contour control: This function looks ahead in the part program to eliminate the acceleration or deceleration and servo delays that limit feed rates when cutting short line segments or contours. It also eliminates machining trajectory errors in corners and small radii.• Nano-smoothing: Nano-smoothing converts CAM-generated line segments into no-uniform rational basis splines (NURBS) curves for faster execution while at the same time improving surface finishes.• Jerk control: By reducing the rate of change of acceleration, vibration is suppressed as is machine shock and the associated machining errors.• Auto-following High Response Vector (HRV): These servo and spindle drive filters suppress mechanical resonance even when the frequency changes.• High-speed Smooth Tool Center Point (TCP): Specifically for high-speed machining (HSM), this function creates a NURBS curve through programmed points, smoothes tool vectors, and controls unwanted acceleration or deceleration to reduce cycle times.
“Adaptive control is an example of added technology that can assist in increasing productivity. The purpose is to reduce cycle time by way of dynamically optimising cutting feed rates in order to reduce chatter and keep a constant chip load on the cutting tool,” says Kushwaha.
Tool identification is another example of a machine tool enhancement that can decrease downtime by scanning tool holders to automatically pick up tooling parameters and input that information directly into the machine tool’s offset register, eliminating operator error.
Improving surface finishToday’s CNC systems typically offer submicron resolution or nano-resolution throughout, from internal calculations and stored values through to the interpolator, the drive system, and back through the position feedback devices.
Kushwaha says, “High-resolution count-per-revolution feedback devices create superior surface finish quality when contouring and this minimises the need for secondary operations, reducing delivery times and part cost.”
Reducing cost per partWhen purchasing new equipment, it is easy to fall into the trap of focusing on the one-time acquisition cost while not fully appreciating all of the recurring costs to run and maintain this equipment.
In today’s just-in-time manufacturing environment, equipment availability, reliability, and productivity all are true cost factors, as are the more traditional energy, operation, and maintenance costs. It is very important to consider the cost of a machine over its lifetime of operation. A reduction in downtime can also yield major dividends in terms of cost per part. The purpose of this is to drive more reliability in addition to higher processing.
“We continue to make improvements in predictive maintenance with new software that can signal a machine failure before it happens. For example, for crash protection, an unexpected torque disturbance control allows torque limits to be set so that the axis will stop or retract when a collision is detected, reducing damage to the machine,” explains Kushwaha.
One of the most important goals in the development of any new CNC is improved machining performance. Faster cycle times and better part finishes are two key areas that developers are trying to enhance.
“By using a new high-performance microprocessor, coupled with improved machining algorithms, we have effectively doubled and even tripled our processing speeds. Our testing has revealed dramatically faster cycle times, yet also a smoother and more accurate part finish,” says Kushwaha.
Reduces cycle time and maintain synchronisation between part systems“M800/M80 series provides ‘Spindle superimposition control’, a feature that enables simultaneous execution of turning and centre tapping, although they needed to be executed individually.
These features are effective in eliminating idle time, resulting in a significant reduction in tact time,” says a spokesperson from Mitsubishi Electric India. This CNC also offers features that maintain synchronisation between part systems, which is required for automatic lathes, in particular. These enable operators to implement ever more complex machining safely and securely.
High productivity and high quality “CNC-dedicated CPU is incorporated in the M800/M80 series, providing signi-ficantly improved short segment processing capability. The benefits are not limited to improvements in basic performance alone. The Tolerance Control function enables operators to achieve high-quality surfaces simply by specifying the desired dimensional accuracy. This feature takes machining to a whole new level,” explains a spokesperson from Mitsubishi.
Brings out the potential of machine toolsM800/M80 series provides new features that can maximise the full potential of machine tools, including – variable-acceleration pre-interpolation acceleration or deceleration provides optimised acceleration, with each axis’ characteristics fully exercised.
“For example, allowing a linear axis to accelerate irrespective of rotary axis responsiveness. OMR-FF control allows for optimal position loop gain adjustment suited to each axis, leading to smoother and more accurate cutting. This CNC has new functionality effective for higher productivity, including rapid traverse block override function that helps reduce non-cutting time by overlapping feed blocks,” says a spokesperson from Mitsubishi.
Dormer’s latestDormer has launched many products for CNC machines. However, the most important ones are explained below by Ahuja.• Two new turning geometries SF and SM, in two new grades T6310 and H07 for Difficult to Machine Materials (DTMM), egstainless steel, nickel and titanium along with its alloys. Both the new grades have the right combination of substrate and coating to enhance resistance to thermal cracking, pitting as well as plastic deformation. This provides additional hardness and increased abrasion resistance to offer greater reliability and prolonged tool life.
• M8340 PVD milling grade -The substrate of M8340 is surrounded by nano-layers of TiN, and TiAlN for increased thermal crack and wear resistance. It then has a layer of TiN, which provides high hardness in combination with oxidation resistance, which improves overall wear resistance, in steels, stainless steels and some areas of CI.
• New milling cutter for machining stainless steel, with OEHT inserts along with XEHT wiper inserts. There are three new positive geometries – MF, MM and M, for various cutting conditions.
Haas’s latest“The Haas DM-1 is a compact, high-speed machining centre built with proven Haas components and sub-assemblies. It is identical in construction and specifications to the DT-1, but with the substitution of a Haas 40-taper inline direct-drive spindle, and an 18+1 side-mount tool changer. Its high acceleration rates, fast rapids, and short tool-change times make the DM-1 an attractive high-productivity machining centre,” says Gupta.
Gupta adds, “For some shops, investing in 30-taper tooling for the DT-1 is not a desirable solution. The DM-1 allows shops to make use of their existing 40-taper tooling, and enjoy the benefits of the larger spindle. The DM-1 is a lean-style machining centre with a compact footprint that allows multiple machines to be placed side-by-side, allowing for the most efficient use of valuable shop floor space.”
Multi Axis’s latestMulti Axis CNC recently developed ‘Double Spindle Mirror or Symetric job machining CNC’ with latest Mitsubishi m70V controllers. “The CNC milling suited to shoe mould industry as well as auto component industry. It enhances 200 per cent productivity. While China pushing their Double Spindle CNC in Indian Market at higher price and customers doesn’t have option but to buy with Chinese controllers that further need after sales and support. While we are using re-owned CNC controller from Mitsubishi-Japan therefore minimal chance of breakdown and ensure productivity. Our machines price is lower than any Indian or imported CNC milling. We have 100 per cent backup for application or support and service,” states Kushwaha.
Wohlhaupter’s latestWohlhaupter has launched the primebore boring head, which covers a finish diameter boring range of 3mm to 208mm. It comes with the same Wohlhaupter quality and accuracy of 2 microns. The serrated design ensures the clamping is strong, ground and lapped construction results in precise movements. This tool comes in a kit as well to cover a boring range of diameter 6mm to 128mm. All accessories to cover this range are part of the kit, inventory management also automatically happens as everything is in a box. Customer can take maximum parameters due to the solid construction and tool balancing thereby getting better productivity.
Khurana says, “Apart from the primebore boring range covered by us of diameter 0.4 mm to 3,255 mm is the largest range in the industry. Above this advantage which we give is servicing support at our Delhi head office, all tools can be serviced at the specially set up service facility. Secondly for precise machining we offer a wide range from 0.4 mm to 3,255 mm boring tools in digital heads. Our combiline tools (Roughing and finishing by one tool) range is 24.5 mm to 3,255 mm which is a first choice in liner bore machining for cylinder block and others similar applications.”
Mitsubishi’s latest• Development of convention-breaking CNCs Leading the way in today’s industrial globalisation, the innovative products of Mitsubishi Electric continue to exceed the expectations of users around the world. “The outstanding performance of our CNC line-up consistently wins praise from users for their high levels of productivity, intuitive usability, and superior functionality. However, to develop the new M800/M80 series, we went back to the drawing board and completely re-examined our cutting-edge control technologies. The result is a breakthrough in the control of high-speed, high-precision machining,” boasts a Mitsubishi spokesperson.• User performance requirements demand a commitment to development    The story of the new M800/M80 series began with conventional development to produce incremental evolutionary improvements. “Our project team determined that the only way to signifi¬cantly boost processing performance and totally satisfy user demands would be the creation of a CPU optimised for CNC control. This insight inspired Mitsubishi Electric’s ¬rest-ever attempt to develop a CNC-dedicated CPU and opened a new chapter in CNC development,” says a Mitsubishi spokesperson.• Smartphone-like intuitive touch operation    The display features a capacitive touch screen that is    commonly used in smartphones and tablets, allowing for intuitive and easy operation. With a simple fl¬ick of the finger, for instance, one can monitor the desired part of program, or view and select a menu key on the next page without the need for tedious key operation. In 3D graphic check, one can view a 3D model at any desired size, in any desired position.
***********TCO and MTBF helps you get a better understanding of uptime, machine utilisation and cost per part.Nitesh Gupta, GM – Product and Business Development, Haas Automation*****************************************We generally ignore to reduce the set-up time, though much can be achieved through it.Gautam K Ahuja, Managing Director, Dormer Tools India Pvt Ltd.*****************************************Capable machines as per component, suitable tools greatly help in productivity improvement.Keshav Khurana, Executive Director, Wohlhaupter India Pvt.******************************************By using a new high-performance microprocessor, coupled with improved machining algorithms, we have effectively doubled and even tripled our processing speeds.
Rajesh Kushwaha, MD, Multi axis CNC