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.

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



KURT Workholding: Vertical Machining Center Concepts

Vertical Machining, also known as milling, relies on rotary cutters to remove metal from a workpiece. Vertical machining occurs on a vertical machining center (VMC), which employs a spindle with a vertical orientation. With a vertically oriented spindle, tools stick straight down from the tool holder, and often cut across the top of a workpiece.

Vertical Machining Benefits
There are many benefits associated with vertical machining, some of which include:

  • Infinite part shape possibilities due to the 3, 4 or 5 axis capabilities
  • Temperature stability
  • Durability and reliability
  • On-board probing
  • User-friendly CNC controls
  • Efficient and cost-effective pallet changers

Vertical Machining Center Applications
Depending on the job we offer a variety of diverse types of workholding to fit all your vertical machining needs.

Kurt Product: MLH35 MoveLock
Machine: Small 2 Pallet VMC
Customer: Job Shop
Comment: 2 part/jaw set allows for high density


Kurt Product: MT8 MiniLock with Hydraulic Power
Machine: 2 Pallet VMC
Customer: Small Products Company
Comment: Fixture holds a variety of different length parts. Changing Stationary jaws allows different width parts.


Kurt Product: DL430 on Subplate
Machine: Variety of VMC’s
Comment: Increase density of parts on machine table. Subplate loads quickly and accurately.


KURT Workholding: Horizontal Machining Center Concepts

The Horizontal Machining Center (HMC) concept favours uninterrupted production work. One reason for this is that the horizontal position encourages chips to fall away, so they don’t have to be cleared from the table. More significantly, the horizontal design allows a two-pallet machine to be incorporated into a space-efficient machine. To save time, work can be loaded on one pallet of a horizontal machining center while machining occurs on the other pallet.

Horizontal Machining Center Applications

There are many benefits associated with horizontal machining, some of which include:

  • Shorter processing time per part – With horizontals’ ability to swap pallets, there is no significant delay between machining cycles for job change-over. Plus, on the tombstone fixtures, various pieces can be completed in a single cycle.
  • Lower prices – Horizontal machining has brought down the overall price per part quoted to customers.
  • Three-side machining – The B axis allows three faces of the part to be reached in one cycle. Parts with similar features can also be machined in the same cycle to ensure accuracy.
  • Complex part machining – Complex parts can now be machined more quickly and cost-effectively than ever before.
  • Advanced tooling platform – Horizontal machining centers take advantage of the latest in cutting tool technology.
  • Multi-customer Response – The ability to run multiple jobs on alternating pallets of the same machine allows use to fill orders for two customers in the same shift.


Depending on the job we offer a variety of diverse types of horizontal workholding to fit all your machining needs.

HMC Applications Examples

Kurt Product: Kurt Vise/Tombstone
Machine: 630mm HMC
Customer: Machine Equipment Manufacturer
Comment: 9 pallet FMS, all Kurt Workholding, 8XLPT vises on two faces, 2″ x 2″ grid on two faces for Kurt ML35.


Kurt Product: Kurt Vise/Tombstone
Machine: 630mm HMC
Customer: Machine Equipment Manufacturer
Comment: 9 pallet FMS, all Kurt Workholding, DL640 and 6XLPT Vises for large variety of work pieces.


Kurt Product: DL430 Three Sided Tombstone
Machine: HMC
Customer: Hydraulics Component Manufacturer
Comment: Unique triangular shape allows large parts to be clamped without exceeding the work envelope


Kurt Product: 5 ea. DL640 & 5 ea. DLU4 Specialty Vise Tombstone
Machine: HMC
Customer: Automotive Tool Products Company

  • Hard jaw vises for rectangular parts and machinable jaw vises for irregular parts.
  • Large parts on one side, small parts on the other. Hydraulically actuated for operator efficiency


Kurt Product: Specialty Vise Tombstone W/ 2 ea. 6XLPT & 1 ea. 8XLPT Vises
Machine: HMC
Customer: Mold Shop
Comments: Large mold bases in 8XL and small mold bases held in the 6XL allows a large variety of parts.


Kurt Product: Specialty Vise Tombstone W/ Four D810’s
Machine: 630mm HMC
Customer: Mold Shop
Comments: Allows clamping for four 10” x 12” mold bases


Kurt Product: CT640 ClusterTowers
Machine: 20 Pallet HMC
Customer: Job Shop
Comment: Job shop environment requires many jobs to be set up and ready to go.


Kurt Product: CTU6 CarvLock ClusterTower
Machine: 10 Pallet HMC
Customer: Hydraulic Manifold Manufacturer
Comment: Unique combination of steps to clamp a wide variety of sizes.