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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.

MILL & KILN PINIONS

Hofmann Engineering specialises in the design and manufacture of kiln and mill pinions of all sizes and specifications. We offer a range of in-house heat treatment options from case carburising, to quench & tempering, as well as induction hardening. Hofmann Engineering has a range of finish machining options including finish grinding to achieve excellent quality levels required. Worn old existing pinions with unknown geometry can easily be replaced and product improved by Hofmann Engineering.  

LARGE MILL & KILN GEARS

Hofmann Engineering specialises in the design and manufacture of large kiln and mill girth gears up to 15 meters in diameter. We offer newly designed and direct replacements for existing gears in several different material specifications including Forged Fabricated, Spherical Graphite Iron (SGI) and Cast Steel. We have a range of finish machining options including 6 specialised gear tooth cutting machines. Worn old existing gears with unknown geometry can easily be replaced and product improved by Hofmann Engineering.

FORGED STEEL FABRICATED GIRTH GEARS

Hofmann Engineering specialises in high strength forged steel fabricated gears up to 15 meters in diameter. The rim steel goes through a unique manufacturing process to help eliminate defects such as porosities often found in castings. The steel starts out as a cast ingot and is forged/reduced down in thickness to the required size. The steel is then heated, quench and tempered to form an extremely tough tempered martensite state yielding high hardness with maximised toughness. Fabrication is carried out in-house as is finish gear cutting on one of our 6 specialised gear tooth cutting machines. Worn old existing gears with unknown geometry can easily be replaced and product improved by Hofmann Engineering, supplying all continents of the world.

OPEN GEAR RECONDITIONING PROCEDURE


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

3) INSTALL HOFMANN CASE HARDENED PINION

4) APPLY HOFMANN PROCEDURE
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

GRINDING MILL SHELLS & HEADS TO DIA 44FT

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.

KILN SERVICES

WORLD WIDE KILN SERVICES

ALIGNMENT:
> 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.

RECONDITIONING:
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.

MAINTENANCE PLANNING:
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.