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| [Servos] [Machines & Drives] [Large Machines] [On-site Services] [Electrical Manufacturing] [Equipment Overhaul] [Electronics] [Engineering] [Calibration] [Asset Management] |
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Mechanical repairs from Dowding & Mills - market leaders in Engineering,
Calibration & Electronics.
Machining Metal loss through wear and corrosion are the main causes of failure in mechanical process equipment. The replacement of metal by welding, thermal spraying, electroplating and restoring the original dimensions by a variety of machining techniques forms the basis of all repair processes for which Dowding & Mills is renown. In addition, the extensive machining facilities are used to manufacture new individual components or complete assemblies, either as part of a repair or as one off or batch requirement. Coatings that can greatly enhance component life are brought together through the BESCOTE System. BESCOTE is a range of technical specifications and procedures, developed by Dowding & Mills, to select the correct material and application process for optimising a repair to meet the customer's specific application. Using the skills of the fitting teams together with these technologies and the handling capacity of up to 60 tonnes, Dowding & Mills is able to recondition complete units such as gearboxes, pumps and presses.
Machining is of major importance in any reclamation process and throughout the network of repair centres, the capability to carry out any machining process is met by a wide range of facilities, which includes: - Turning Lathes are capable of accepting work from the smallest components up to the very largest rollers and equipment, from the heavy industries such as cement and steel. Boring A range of horizontal and vertical borers allows a variety of work to be handled, from small components to large items of plant. These include the line boring of gearbox and pump casings. Milling Universal, Horizontal and Vertical Milling is carried out to meet the requirements of customers, from basic keyway cutting to the machining of slideways. Key branches are equipped with large Elgamill capacity. Grinding
Super Finishing By using the latest microfinishing machines, customers can specify repeatable surface finishes of less that 1μ in. CLA. CNC For customers with requirements for batch-work, the manufacture of complex components or repeat spares, the division has invested in CNC turning and machining centres. Turning facilities enable the production of components, from the simplest pin to shafts requiring up to 8000mm between centres and a swing of 1500mm over the bed. With integral milling and grinding attachments, a component can be completed in one setting, including the cutting of keyways and the grinding of journals. The CNC machining centres manufacture components such as cams, dies, indexing plates, gearboxes and spare parts for all types of mechanical machinery. Gear Cutting
Dowding & Mills uses a comprehensive range of reclamation welding processes
and has experienced engineers to determine the most effective method
for a particular application. MIG MIG is used for high deposition rate welding and offers a wide choice
of metals to overlay or match parent material to a high quality. Steel
castings, shafts, fabrications and aluminium pistons can be reclaimed
using this method. TIG TIG is used extensively for customers in the plastics industry, where
perfect coatings of cobalt alloy are required on extrusion screws. However,
it can also be utilised for hard face deposition on gland areas in pumps
and on valve seats. Hot Wire TIG
Submerged Arc Submerged Arc is used for heavier deposits onto large items of plant
from industry, such as crane wheels, rollers and shafts. Using rotary
welding of this type ensures that any stress build-up is evenly distributed.
Spiral Welding Spiral Welding, in either its MIG or TIG form, is a fully automated
process and can be used for small and medium diameter shafts. It is
particularly beneficial in reclaiming acid resistant pump shafts, splined
shafts and impellers. Manual Metal Arc Manual Metal Arc is used extensively for a wide
variety of specialist repairs to iron castings, such as engine blocks,
using ferro nickel consumables. Because it is very portable, this process
is particularly useful for on-site work.
BESCOTE System
Dowding & Mills has established the BESCOTE system to facilitate
the selection and application of the most suitable and cost effective
surface or coating, be it by welding, electro plating or thermal spraying.
BESCOTE takes full account of the component's operating environment,
its base material, working temperature and any corrosive or erosive
conditions, as well as life cycles and costs, to provide optimum performance
from a component repair.
Electro-Plating
Both hard chromium and heavy nickel plating facilities are available
from branches throughout the UK. With plating tanks amongst the largest
in the country, the majority of industrial plating work can be accommodated.
Hard Chromium
Hard Chromium produces a metal coating with a low co-efficient of friction
recognised for its hardness and wear resistance.
Mining equipment, rolls and cylinders all benefit from the reduced
wear rate and anti-corrosion properties, whilst the low co-efficient
of friction makes chromium an ideal coating for bearing journals, crankshafts
and hydraulic rams.
Nickel
Nickel can often be used under chromium for corrosion protection or
where heavy deposits are required. Nickel alone can provide an added
protection to components operating in highly corrosive atmospheres or
chemical solutions.
Thermal Spraying
Dowding & Mills offers all forms of Thermal Spraying, currently
available, which can be used to restore component dimensions with similar
materials to the original. However, using today's more suitably engineered
coatings results in increased life without distorting, cracking or inducing
embrittlement into the base material.
Combustion Wire
This method provides a high quality, cost effective and fast turnaround
process for rebuilding small to medium size components, such as bearing
areas on pump shafts and motor rotors. It uses wire drawn consumables
such as carbon and stainless steels, copper, nickel alloys, zinc and
aluminium.
Electric Arc
This is particularly suited to the reclamation of larger components
such as hydraulic rams and printing cylinders. Two wires are used, usually
of the same composition. However, dissimilar metals like carbon steel
and copper can be used to form pseudo alloys to give high resistance
to wear, with good heat dissipation properties for clutch plates.
Combustion Powder
This process deposits any type of powder that can be melted in an oxy/acetylene
flame. Though materials of similar composition to wires can be deposited
in this way, it is more commonly used for spraying oxide ceramics and
fused hard facing alloys. The most popular applications with customers
are fused, coated pump plungers and steel works rollers.
Plasma
Generating gun temperatures that are hotter than the surface of the
sun to melt any powdered consumables, plasma coatings are of superior
quality and integrity, being extremely dense and well bonded. Ceramic
oxides of chromium, aluminium and titanium give longer life, whilst
oxides of Zirconia give an excellent thermal barrier.
HVOF
The HVOF system's strength is in the application of tungsten carbides
and chromium carbides to improve wear-life on fan-blades, pump casings
and tile moulds. Some of Dowding & Mills' latest developments in
this field position the company at the forefront of Surface Engineering
technology.
White metals of varying grades have long been used as an anti-friction
material for lining bearings. The applications include bearings for
turbines, gearboxes, internal combustion engine crankshafts, stern tubes
and fans. As with other metal replacement processes, white metalling is dependent
upon thorough preparation, top class quality control procedures and
a wealth of experience, not only to carry out the work, but also to
select the appropriate grade metal. New metal, to a national or international
standard, is always used as premature failure from inclusions and gas-induced
cavities can occur through using reclaimed material.
Temperature controlled melting pots ensure the metal properties are
maintained at the highest level and non-destructive testing, such as
ultrasonic, is then used to check the quality of the bearing and its
bonding with the supporting shell.
Dowding & Mills' extensive machining facilities
mean that the finishing of bearings is equally controlled in respect
of quality and delivery. Dowding & Mills - Engineering, Calibration & Electronics Services |
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