Frequently asked questions
About
Hardfacing
OF VM’s
What types
of wear materials
can be hardfaced?
Most white cast irons, especially the softer type such as Nihard 1 to 4. Also Cr 27 and Cr 20 can be hardfaced.
What type
of hardfacing material
should I choose?
Cr carbide (IBER 250) and Cr-Nb carbide (IBER 450) are the standards but other alloys of Complex carbides can be used for specific applications.
IBER 450 is approximately 30% more resistant than IBER 250 and a combination of both is suitable.
How hard
is the hardfacing?
The welding is done “cold” and the hardness obtained is 60-65 HRC.
It is necessary
to pre-heat?
No. The temperature should be kept lower than 90ºC to produce as hard a surface as possible, with a fine carbide structure. When welding at these temperatures the hardfacing cracks continuously relieving stresses.
Can segmented
wear parts be
hardfaced?
Both segmented grinding tables and rollers can be hardfaced. In fact, it is safer to hardface segments than full tires (rings). Tires have a high risk to crack if the suitable welding procedures are not followed. The segmented design is “pre-cracked” but safely bolted on.
How much
hardfacing can be
put on an hour?
Depending on the capacity of heat dissipation, the normal welding parameters settings allow 5-6 kg/h to be deposited on small items and 8-10 kg/h on larger ones.
How long will
the hardfacing
last?
Normally the wear life is more than double that of the original cast wear parts.
How thick
a layer can be built
up per pass?
Normally a bead size of about 3mmx8mm using a Ø2,8mm wire.
IS The hardfaciNg
a cost-effective
solution?
Yes. The cost of hardfacing in €/ton of mill production is about half that of changing the segments.
When calculating the cost, the improved availability of the mill should be taken into consideration, once it is possible to avoid the normal reduction in production rate as wear progresses with hardfacing, by rewelding more often than changing segments.
Studies have shown a reduction in maintenance costs of up to 50%.
How many
times can I weld
table liners?
There is evidence of more than 20 times.
How many
times can I weld
the rollers?
There is evidence of 10 times or more, either for segmented or roller tires.
What is
the maximum layer
thickness?
In principle there is no limit: up to 80mm has been achieved but it depends on the type/size of the mill. Typical layers are 20-45mm thick.
What
can possible
go wrong?
If the hardfacing is not carried on by an experienced company following the correct procedures, the segments can distort and become loose, roller tires can crack, the welding current may flow in the wrong direction burning the roller’s bearings and bearing shoes of gearbox can “run” dry. The hardfacing may spall off the parent material also if metal parts come into the mill during operation.
can i have a
work report?
Yes, for any hardfacing work performed by our teams, the appropriate report is provided to the customer.
Frequently asked questions
About
Ibermill
How
do i get
a quote?
Through any of our contacts: website or email. Mobile phones are always an alternative in case of need.
Does
Ibermill have
references?
Our technology and consumables are approved by all the major cement groups and vertical mills OEM’s as well, which means that our portfolio cover all the types of VRM´s in different geographies.
Does
Ibermill visit
the sites?
Yes, whenever it justifies, either for mill inspection and follow up or for preparation of the first work on site (standard included on the price offered).
Does Ibermill
manage all the
work logistics?
Normally yes. For the works on site, we arrange the transport of equipment and welding wire to site, travel food and accommodation for our specialists. There are very rare exceptions in case of customers outside EU. For the repair of spare parts in the workshop, we can also arrange for the transport of the parts as well.
How is
the work on site prepared?
In the first contract, it’s a standard for us to make a preparatory visit prior the work, for mill inspection and agree the technical details. Before any work start, we send in advance a Job Preparation Document (JPD), with all the required tasks prior to our arrival.
Do I need a local team
to permanently support
Ibermill on site?
No. If the customer comply with the preparatory tasks listed in JPD, our team just need local support on the first working day, for lifting the equipment and welding wire to mill platform and establish the electrical connections.
What are the normal
working hours and size
of Ibermill team on site?
In case the local work legislation permits, our standard is working 24/24h in 2 shifts of 12h, 7 days a week. Our normal team has 2 specialists in each shift and 1 supervisor for the whole duration of the works.
Can Ibermill
work in two places
at the same time?
Yes, depending on the dimension of the work, we can work in 3 or 4 places simultaneously.
How fast
can Ibermill respond
an urgent request?
Depends on the site location. In Europe 1 week is sufficient for transport the goods to site. If equipment and wire is available on site, 2 days for the team travel it’s achievable.
Does Ibermill
use subcontracting?
No, and this is a must for us. Being a very demanding activity and of great responsibility, we only work with our well trained and experimented own staff.
What is the most advantageous solution
to renovate spare parts of VRM’s?
On site or in the workshop?
Financially speaking and despite the increase of transport costs, normally the workshop solution is more advantageous. The big and segmented rollers are normally the exception in case of availability of a complete spare roller (hub) on site.
What is the biggest size of
spart parts that Ibermill can
repair in the workshop?
Rollers: 10 tons/Ø2,8m | Table: 60ton/Ø6m | Roller press shafts: 30tons