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Mills & Kilns

Hofmann Engineering has a long and successful history of designing, manufacturing, installing and servicing mill and kiln parts. With a capability of manufacturing girth gears up to 15m (49ft) diameter and shells up to 13.4m (44ft) diameter, Hofmann Engineering is in a unique position to supply these large parts. Hofmann Engineering also has the experience and expertise to manufacture high quality pinions, gearboxes, inching drives, gear reducers, bearings and couplings for mills and kilns, as well as having a long history of supplying lubricant and lubricant systems for these products.

Please contact Hofmann Engineering for any of your mill or kiln part requirements.


Specialising in the design and manufacture of mill and kiln pinions of all sizes and specifications. A range of heat treatment options including case carburising, quench and tempering, and induction hardening are available. Pinions can be finish ground to achieve a superior quality level. Old, worn, existing pinions with unknown geometry can be easily replaced with a product improved pinion.


Specialising in the design and manufacture of large mill and kiln girth gears up to 15 meters in diameter. New designs or direct replacements of existing gears can be manufactured. Materials offered include forged fabricated steel, spherical graphite iron (SGI) or cast steel. A range of finish machining options are available including a number of specialised gear tooth cutting machines. Old, worn, existing gears with unknown geometry can be easily replaced with a product improved gear.


Specialising in high strength forged steel fabricated girth gears up to 15 meters in diameter. This is the manufacturing process producing superior girth gears. The rim steel undergoes a unique manufacturing process to eliminate defects, such as porosities, often found in castings. The steel starts out as a cast ingot and is forged to a third of its original thickness. This ensures a much stronger and more uniform grain structure with no inclusions. The steel is then heated and quench and tempered to form an extremely tough, tempered, martensitic state yielding high hardness with maximised toughness. Old, worn existing gears with unknown geometry can be easily replaced with a product improved gear. Shipping can be arranged to all continents of the world.


1) WORN GIRTH GEAR                                          2) WORN SOFT PINION
1) With less than 0.5mm of involute wear.                
With over 5mm of wear.


a) Measure involute wear on gear.
b) Clean and crack detect gear using magnetic particle method.
c) Install Hofmann case hardened Pinion. Case hardness must exceed 55HRC.
d) Laser align drive train.
e) Accurately in situ grind girth gear using the case hardened pinion as a master.
f) Apply Hofmann Grafloscon A-C1 Ultra primer to pinion and gear.
g) Inspect lubrication system and connect running-in lubricant Hofmann Grafloscon B-SG00 Ultra.
h) Start gear drive slowly increasing the power as the contact improves.
i) Apply repair Chemical Etch Hofmann Grafloscon D-SG00 Ultra to heavy contact areas until good contact is achieved.
j) Monitor and completely document the installation procedure.

5) FINAL GEAR CONTACT                                     4) FINAL PINION CONTACT


Hofmann Engineering has the skills and comprehensive experience working with all the major OEM players and direct to mine sites supplying fabricated Mill Shells to the mineral processing industry.

We have two extensively equipped manufacturing sites for the supply of Mill Shells at Perth (WA) and Bendigo (VIC). Both sites have supplied our largest Mill Shells to date, 11.58m (38 feet) diameter mill shells, however we have the capability to manufacture 14.0m Mill Shells at Perth.

We are experienced in manufacturing shells in various materials that include the following:

• Structural Steel such as ASTM A36, AS3678-250 and AS3678-350
• Duplex Stainless Steel such as LDX2101 and SAF2205
• Carbon Steel with explosive bonded Duplex Stainless Steel cladding.
• Hybrid shells with Steel Flanges welded to Duplex Stainless Steel shell bodies.

The extensive range of shell configurations supplied include Trunnion Bearing supported Shells split into varying configurations such as 1 x 360°, 2 x 180°, 3 x 120° and 4 x 90° sections. In addition we supply Shell Bearing supported Shells which tend to be of smaller diameter sizes than the traditional Trunnion Bearing type and typically a 1 x 360° configuration.

Smaller Trunnion supported Mill Shells tend to have cast heads and can come with an integrated trunnion or with a separately attached trunnion. Larger Shells often require a fabricated head with a bolt on cast trunnion. These heads due their size, tend to be split in the same configuration as their parent shell, 2 x 180° etc. Hofmann Engineering has the capability and equipment to supply fabricated Mill Heads in the same materials as the shells and/or supply Heads and Trunnions in cast Steel or SG Iron.

In the event of an unplanned emergency breakdown, Hofmann Engineering has an impressive history in supporting our clients with the supply of Fabricated Mill Heads with integral trunnions, manufactured in a very accelerated delivery schedule and transported to site anywhere in the world via an Antonov heavy cargo plane. Our current best time was manufacturing completed in an industry record of 4 weeks from design to final customer inspection.



> Survey carried out using hard contact and fixed datum method.
> Tyre and roller diameters are measured during normal operation with the aid of electronic measuring device that is accurate up to 0.10mm. This allow accurate profiling for wear conditions and averaging for alignment
> Basis of the alignment is to achieve correct alignment of the units actual centre line which in turn is positioned in relation  to the meshing characteristics of the main drive girth gear and pinion.

Rollers and tyres can be machined, ground or linished to recondition tyre and roller surfaces, correcting any uneven wear and or taper using our purpose built reconditioning unit.
Our purpose built reconditioning unit can be adapted to suit most rotary kiln designs and can be transported world wide to meet customer requirements.
Tyre and roller diameters are measured prior to and after reconditioning to confirm profiles are flat and parallel to the centre line axis.

Major maintenance projects need careful planning to ensure timely and correct performance.
Correct procedures and methods required in order to obtain equipment performance on start up.
Alignment tolerances maintained during installations and repair outages.