MAPAL: Milling Fibre-Reinforced Plastics

The High Requirements of Milling Fibre-Reinforced Plastics

 

 

 

 

 

 

 

The Machining Task

The machining of CFRPs (carbon fibre reinforced plastics) places high requirements on the tools used, their geometries and coatings. Due to the abrasiveness of carbon fibres in relation to the cutting material, standard tools very rapidly become blunt and the end of tool life is reached after only a few parts. To be able to cut carbon fibres that are laid in a matrix form, increased performance at the cutting edge is required. This statement applies above all if the carbon fibre content is more than 60 %. On milling the peripheral contour on a 21 mm thick structural part for a sports car, the customer had a clear requirement to double the tool life from the previous 10 parts to 20.

The Challenge

The challenge is to keep the milling tool sharp and therefore to prevent delamination at the part edges produced. In this way expensive, manual re-work is saved. At the same time, the issue is to reduce the machining time and to realise long tool lives.

 

 

 

 

 

 

The Mapal Solution

The eight cutting edge, diamond coated solid carbide end milling cutter OptiMill-Composite-Speed has a high performance geometry with a serration. This serration makes possible improved chip removal and therefore an extremely high volume of chips in one machining step. As a result the machining is undertaken using only one tool in one step and the roughing step necessary previously is saved. With twice the feed and three times the material removal rate the tool life is increased fourfold and the quality requirements in relation to surface roughness reliably achieved. As a result the customer’s expectation in relation to tool life were exceeded by a further 20 parts.

The MAPAL Effect

  • Four times the tool life reduces the tool costs
  • Doubled feed halves the machining time
  • Only 1 machining step

 

 

 

MAPAL – Miniaturised Clamping Chucks

Thanks to additive manufacturing, MAPAL now offers hydraulic chucks in miniature format with HSK E25 connection, for example for the direct clamping of tools with a diameter of 3 mm. These meet all the demands on chucks for the miniature sector with respect to radial run-out accuracy, balancing value, cooling lubricant supply and handling.

In order to guarantee perfect radial run-out accuracy, innovative clamping chamber systems are integrated into the new chucks that fit tightly against the shank of the tool. They are fitted with dirt grooves as protection against micro-soiling. The demanded balancing value is ensured thanks to the internal balancing geometries and supporting structures that also aid the optimisation of weight and strength. The miniature chucks allow homogeneous acceleration and deceleration of the whole tool system of chuck and tool for less loading of the spindle.

The innovative manufacturing method has also enabled the chucks for the miniature sector to be equipped with decentralised coolant outlets. These outlets are designed using parameters such as coolant pressure, setting dimension and spindle speed so that they deliver the cooling lubricant precisely to the cutting edge. In the best case, a metered total-loss lubrication system is achieved that eliminates the need for subsequent cleaning of the parts.

The new miniature chucks from MAPAL allow quick and simple clamping of the tool. Neither training courses nor high setup costs or expensive peripherals are required for implementation of the chucks.

The new small hydraulic chucks also offer new possibilities for the clamping of workpieces. For example, for the clamping of artificial hip joint balls. Specially formed clamping chambers inside the chuck and a special outside geometry ensure that the balls are very precisely and at the same time gently clamped. Particularly in medical technology, topics such as reproducible precision are taking on enormous importance – and this is ensured during machining thanks to the new chucks.

Please contact us for more information.

 

MAPAL – Machining of Unstable Structural Parts

 

Thin-walled parts are used in a wide variety of applications. These components are often manufactured close to the net shape, but nevertheless require a great many machining operations. The particular challenge for these machining processes is that due to their design, these parts are very unstable and susceptible to vibration. That creates special demands upon the design of the process and the tools.

These parts are preferably machined in a single clamping system. In order to meet this demand and to make as many of the surfaces to be machined as accessible to the tools as possible, certain allowances have to be made in the clamping system. As a consequence, the workpiece is not optimally supported and tends to vibrate. Thin webs, voids and interruptions to be machined and widely fluctuating stock removals from the cast blank also call for special tool solutions. For large parts with many machining steps, this would require a huge number of tools. The merging of these steps using combination tools in order to reduce the non-productive times and the number of tool slots is an ideal solution.

Thanks to its vast understanding of the processes for the machining of unstable structural parts, MAPAL is able to offer cost-effective and reliable processes. Three aspects are of particular importance here. Firstly the adjustment of the cutting rate is a factor for reducing or avoiding rising vibration. Both vibration of the tool – which would result in short tool lives and poor machining results – and vibration of the workpiece have to be prevented. The latter would result in a recoiling of the part against the cutting edge and could cause damage to the tool. The second important adjustment in the tool design is the evaluation of the tool body. Vibrations can be reduced here by an appropriate design and choice of material. Furthermore, an intelligent arrangement of the cutting edges in form and position helps to keep the cutting forces low. And finally the machining process itself offers possibilities for reliable machining of parts susceptible to vibration. Reorganization and the choice of alternative sub-processes create a change in the distribution of forces that can increase the process reliability. For example, the use of a circular milling operation instead of a solid drilling operation can help to stabilize the process.

Please contact us for more information on machining of Structural Components.

– This article is an excerpt from Mapal Innovations – Process Solutions 

MAPAL: Machining of Valve Seat and Valve Guide

Modern precision tool provides more production capacity with lower costs at the same time on the machining of Valve Seat and Valve Guide

Machining Task
The machining of the valve seat and valve guide is one of the primary cost drivers during the machining of cylinder heads. Exact angles at the sealing chamfers on the valve seat rings and close tolerances on the concentricity between valve seat and valve guide must be met. In addition to the high geometric requirements, the increasing requirements on the high-temperature stability of the valve seat rings mean that in general very hard and difficult to machine sintered materials are used.

Challenge
The tool concept that meets these requirements while reducing costs at the same time must make use of the most suitable cutting material and have corresponding precision. Cutting material and insert geometry are responsible for the tool life and make a significant contribution to the costs per workpiece. However, the overall design of the tool is also important.

Our Solution

The solution for these tasks is a MAPAL tool with indexable blades and guide pads. It guarantees a qualitatively flawless result due to the high precision of the inserts, the insert seats and the connection in relation to the valve guide. The HX inserts for machining the chamfers on the valve seat ring are of a hexagonal shape and have six cutting edges. Due to a clever arrangement, these inserts can even be used several times for the different chamfers. The precision insert seat in which the HX inserts are mounted makes it possible to change the inserts without any setting process, as all the angles match exactly.

Conversely, all the tools previously used for this machining task require to some extent time-consuming setting work on an insert change. Also it was normally necessary to set the radial run-out on the replacement of the valve guide reamers mounted in the base tool. In the new MAPAL concept the tool for machining the valve guide is now connected using the proven HFS connection. The tool is changed with a radial run-out accuracy of < 5 µm by simply screwing in or unscrewing. This very stable connection also makes it possible to increase the feed rate.

MAPAL Effect
The comparison of the conventional system with the MAPAL solution produces a very clear result. The much higher feed rate and the related cycle time reduction result in a significant improvement in the production capacity, or even in less investment in machinery for new projects. As no setting work is required and it is only necessary to change inserts and tools, there are also significant savings in the area of the non-productive times. However the most important effect on the costs per workpiece is the inserts for machining the valve seat rings. Due to the stable mounting, the right PcBN grade and the ideal cutting edge geometry, the tool lives are increased by five to ten times compared to other systems.

Cycle time reduction due to much higher feed rate
Setting no longer necessary
Five to ten times higher tool lives