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Gear Skiving Machine

KPS21 / 30

A Highly Rigid Dedicated Machine Delivering a Highly Efficient Machining of Small and Medium-Sized Internal Gears

Max. Workpiece Outside Diameter
200mm / 300mm
Max. Module
1 / 4
  • Feature
  • Specifications
  • Catalog

Typical Parts Hobbed

Internal Gear for Small-Sized Gear Reducer
Internal Gear for Medium-Sized Gear Reducer
Automotive Transmission Gear

Gear Skiving

Gear Skiving is a type of gear generating cutting method, in which a cutter is fed in the direction of the part axis with a certain axis angle while rotating both the part axis and the cutter axis at a rotation ratio corresponding to the gear ratio. During the cutting cycle, cutter blades of the tool machine a part little by little by skiving the tooth space. So, it is called as “Gear Skiving”. Not only internal gears but also external gears can be machined.

Highly Efficient Machining of an Internal Gear – High Speed Cutting

Machining time can be reduced because machining is carried out by rotational motion instead of reciprocating motion of tools like a conventional gear shaper.

Highly Efficient Machining of an Internal Gear – Lead Modification

Lead modification such as crowning or taper which was impossible with a conventional broaching process can also be performed without changing the machining conditions or increasing the cycle time. The ability to adjust the lead increases the degree of freedom in gear design, reducing finishing stock removal in the post-process and reducing tool costs.

Highly Rigid Body Structure

The bed, column and other main machine core parts utilize the technology cultivated in hobbing machine manufacturing to ensure high rigidity and enable powerful cutting.

Hard Gear Skiving (Optional Specifications)

The auto part orientation device automatically detects pre-machined teeth and enables finishing of a heat-treated part.

Automation in Production Line (Optional Specifications)

A long production run and frequent tool changes are possible with the use of a ring loader and Automatic Tool Changer for part load/unload and tool change-over.


  • Machine Type




    Max. work piece outside diameter



    Max. Workpiece Module



    Max. Cutter head swivel



    Max. revolution of cutter, infinitely variable



    Max. revolution of work spindle






    Floor Space: Length x Width x Height



Product Catalog

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Inquiries about This Product

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Vertical Hob Machine

Changing Fixtures, Hob Cutters or Workpieces (manual loading) is far simpler and faster than in a horizontal hobber as compared to a vertical hobber. As the workpiece /fixture are positioned vertically, they are very easy to exchange and accurately mount. The Hob Head of a vertical hobber allows great accessibility to the work table/tooling area and peripheral equipment (auto loader, transfer unit etc.) can be added without reducing operability!


Hand Scraped Guideways

Kashifuji hand scrapes the guideways on all its hobbing machines to create a platform that dampens and absorbs the intermittent cutting forces that are inherent to hobbing process. This feature allows many years of use while still maintaining superb hobbing accuracies.

Generally, machining has limited achievable accuracies due to friction created distortions and/or internal stress relief produced during the machining process. Variations of temperature and humidity during the machine process can also reduce accuracy. Kashifuji utilizes a hand scraped surface finish to assure highly accurate guideways that are not possible by any machining/grinding process.

Hand Scraping is a finish processing method that makes the guideways extremely accurate with an ideal flatness and straightness by manually removing metal in extremely small amount (1~3 micro meters) by the use of a hand tool called a "Scraper". This hand tool has a carbide tipped single edge blade with a blunt angle. This tool is used to relieve the surface tension (create numerous, evenly distributed small, shallow dips or reliefs) in the guideway surfaces. Scraping produces a very flat surface, and the "shallow divots" retain oil which creates smooth sliding surfaces while reducing wear.


Hand scraping is a labor intensive process. The guideway surfaces are painted with a “dye” then rubbed with a reference straight edge, the dye collects on the highspots. The highspots are then removed by “hand scrapping”. This process (applying dye, rubbing & scrapping) is continually repeated until approximately 30% of the guideway surface is “relieved” producing ~70% bearing surface. This process produces an extreme flatness.

Hand scraping is referred to as a "Master's Skill". Kashifuji's skilled craftsmen are able to make accurate micro-meter scraping marks compensating for variations caused by material or temperatures changes. The "scraping pattern" produced, is often referred to as an "art form", and is unique to each craftsman. It takes many years of tedious, difficult work to acquire the experience & skill to become an accomplished Kashifuji "Scraper".


Zero Backlash Table(Work Table Backlash Eliminator)

Kashiufji designed and developed a hydraulically controlled split worm Work Table Backlash Eliminator.

This device creates a Zero Backlash condition for the work table under all cutting conditions. The backlash eliminator suppresses work table vibrations assuring smooth and highly accurate work table rotation. The rotational accuracy of the work table will not degrade with use, as the device is self-adjusting (maintenance-free).

The backlash eliminator allows consistency in hobbing accuracies especially when hobbing large pitch gears, hobbing with a carbide skiving hob cutter and opposite hand hobbing (lead angle of a hob cutter is opposite of the helix angle of the part).



Numerous styles and types of auto loaders, conveyors or part stockers are available for automatic part transfer. All loader design are labor saving and increase efficiency.

Basic 2-Arm Auto Loader(KN80, KN152)


Basic Ring Loader


Transfer Example for Flat Gears


Transfer Example for Flat Gears


Transfer Example for Shaft Gears


Transfer Example for Shaft Gears


In-machine chamfering unit (optional specifications)

<Stock removal process using a chamfering cutter>
The use of an auto part loader device enables chamfering and deburring during the hobbing process. By effectively using the open space of the machine and by making the chamfering tool axis and the deburring tool axis independent, it is easy to change / adjust the tooling from the machine front operation side. In addition, the combination of hobbing, chamfering and deburring reduces the line length and cycle time.


By installing a chamfering device underneath the hob head, it is possible to chamfer the part in the tooling area after hobbing and deburr the part in the open space. Additionally, the secondary burrs caused by deburring can be removed by re-hobbing. The removal of secondary burrs prevents the tooth flanks from getting damaged due to the hardened secondary burrs in the finishing processes such as gear grinding or honing, contributing to improved tool life. The combination of hobbing, chamfering and deburring reduces the line length. Also, it is possible to process a shaft gear.


<Milling Method by tracing using a carbide rotarty end mill>
The use of an auto part loader device enables chamfering during the hobbing process. Using the machine open space effectively, the rotating carbide end mills lightly touch the rotating part allowing chamfering for both top and bottom ends of the part. Chamfering is possible using the same rotarty end mill even if the part type is chgangred.


Hard Hobbing

Hard Hobbing is a finish hobbing process for hardened gears.

There are two kinds of Hard Hobbing processes that use carbide hobs. One is "Finish Hobbing" in which hardened gears are "finished" after the initial tooth cutting. The other is "Hardened Solid Gear Hobbing" where hardened solid gear blanks are finished hobbed.

Kashifuji has developed an Auto Part Orientation Device utilizing a special non-contact sensor that quickly and accurately orientates gear teeth to the hob tool.

Finish Hobbing


Hardened Solid Gear Hobbing


Auto Part Orientation Device



Programs are created by only inputting part gear data, hob data and cutting conditions. After the completion of the programs, hobbing will be automatically performed by selecting the part number.
Optional crowning, relieving and/or taper hobbing cycles are easily performed. Simple and easy-to-operate hobbing programs are available for a wide variety of production situations, from mass production to special prototype hobbing.