Based in the industrial city of Burgos in Northern Spain, machine tool builder Nicolás Correa is recognised as one of the foremost manufacturers of large volume milling machines in Europe. The company’s technology has evolved over its long history to offer customers some of the most flexible solutions for these demanding machining needs. Ed Hill visited its headquarters to discover more.
Anything large-scale inevitably impresses but when walking around the Correa factory in Burgos, Spain it’s not just the immense size of the engineering that is required to make its machine tools that’s astounding, it’s also the obvious skill, passion, technical know-how and dedication that resonates from its walls.
Celebrating its 75th year in business, the Correa Group began life with just 12 workers in the town of Éibar making small milling machines. However, through the 70s and 80s, as competition from German and Japanese machine tool manufacturers increased, the company had to find new markets in which it could compete. This led to the gradual transition to building more bespoke machine tools inevitably required for the large volume end user.
“Over time we evolved to building large volume milling machines with a high level of customisation and flexibility. It’s the opposite of mass production as each machine is a special project,” Javier García, marketing and applications director, at Nicolás Correa explains.
The machines may be tailor-made but the numbers are still significant. Correa has produced more than 900 bridge type machines, 1,000 floor type machines and 3,500 bed type milling machines that can be found in countries all around the world working in sectors such as power generation, automotive, aerospace, marine, oil and gas, railways and more.
The only machine tool builder quoted on the Spanish stock exchange, it employs around 350 people and in 2021 its turnover was €76.5 million. Correa exports 90% of its machines to more than 20 countries. And it also has a substantial manufacturing operation in China and commercial divisions in the rest of Asia, India, Germany and the USA. In 1988 it moved to its extensive manufacturing plants in Burgos, one of the first companies to move to this rapidly developing industrial region.
The company now offers a wide range of large milling and also turning solutions in different configurations consisting of bed type machines (Xperta, Norma, Norma MG); travelling column models (Norma L, Fenix, Axia, Magna); bridge type machines (Fox and Verxa); gantry machines (Fox M, Verxa M, Verxa MW, Verxa MXL, Verxa MWXL and top gantry milling machines (Orix and Xpider).
These are further customised by features such as moving and rotary tables, automatic head and tool changers, robotic tool changing, pallet changing systems, boring and turning capability and even grinding.
Customers in the UK include the likes of BAE Systems, Babcock, Lockheed Martin, Jaguar Landrover and JCB as well as a host of well-known tier one and tier two suppliers.
Apart from the machine bed castings, virtually everything at the company is produced and assembled in-house from the group’s industrial subsidiaries. At Correa Hypatia the smaller bed-type machines are made along with automatic tool changers. Correa Electronica assembles and fits the electrical systems and Correa Steelworks designs and manufactures the thick plate welded components such as the columns, cross beams and rams and supplies the thin plate parts such as operator´s cabinets, enclosures and splash guards coated at its paint shop.
There is also the Correa Service division which aside from providing the aftersales service and support for new machines also retrofits second-hand Correa machines as well as other makes.
Exemplary precision engineering lies at the heart of the Correa ethos. Because it builds machines that have to provide micron accuracy over lengthy travels, every aspect of a machine’s stability, thermal performance and robustness is engineered with minute attention to detail.
The machining of all guideways is carried out by its own tried and tested Correa built and developed machines. It has also introduced innovations such as filling machine columns with high density concrete to give greater rigidity in the frame, or on larger travelling column machines, utilising what it describes as box-in-box construction to support and guide the column and the ram symmetrically meaning even greater accuracy can be maintained at the spindle despite the immense forces it undergoes while rough machining, for example.
“At Correa we believe the fundamental performance of a machine is based on its mechanics,” Mr García says. “The forces our machine tools have to contend with when heavy roughing can be massive. If you want a machine that can handle these forces over a long period of time it’s vital to have good mechanics. It’s similar to a highly engineered mechanical wristwatch compared to a digital one.”
Nowhere is this approach more apparent than in the mechanical machining heads that Correa produces. However well engineered the structure and stability of these large machines, if the head performance cannot match it, machining any part or material will be problematic.
Correa offers 12 different types of head ranging from simpler boring and 3+2 indexing heads to 5-axis heads and multitasking options. For example, its UDX (universal auto indexing) mechanical head – incorporating its own patented technology – is capable of providing 162 million tool positions driving the spindle at 10,000rpm.
“The head is the most precise part of our machines,” Mr García affirms. “Tolerances are minute; two or three microns for the cylindrical parts. They need to be as compact as possible and because they are machining large parts that often cannot be moved, they need to be able to universally travel around them and machine every face possible. Each one is essentially hand-built here in Burgos.”
The heads are water cooled to counter the heat generated by machining and before being fitted to any Correa platform they undergo 72 hours of continuous testing.
Solutions and support
Correa’s approach is not just about building and selling machines – it recognises that this has to be backed by substantial customer support, especially when they are purchasing complex, and what might be unfamiliar large machines, to the end user.
“We sell solutions not just machines,” Mr García says. “We collaborate with our customers to ensure that they use them in the most efficient way. Aside from our own research and development, we have an engineering application team who have great expertise when it comes to achieving the maximum productivity. When you buy a Correa machine you are not just buying the milling machine you are buying the training and our full support when you start production.”
Correa engineers are sent around the world to support customer installations and early production. Its sales partners are also well equipped to support customers in their various markets too with Correa trained engineers to provide support.
Perhaps the most notable example of this is Correa’s relationship with its British sales partner DTS UK. The agent’s service manager for Correa, Denis White, is actually based full-time at the headquarters in Burgos with all the service, parts and engineering support readily to hand. So, when a UK customer phones DTS for support it’s more than likely Mr White will be taking the call.
“The UK is a very important market for us,” Mr García comments. “Our market share is very good compared to other manufactures of large-scale milling machines in that country. A big part of that success is because we have a partner like DTS. Their support is very good, their relationship with their customers is excellent and our machines perform well in the kind of industries in which they are used there.”
The reason for all this engineering expertise ultimately comes down to Correa providing its customers with the most productive machines possible. When all’s said and done removing chips from the workpiece is what really counts. That not only means fast processing machines but also reliability with as little downtime as possible, highlighted by the fact that Correa gives a five-year warranty.
“Stock removal capacity is one of the main pillars of our product design strategy,” Mr García says. “We know how to make machines that give the customer the maximum chip removal rates. Our own gantry machines at the factory here in Burgos are still performing well, roughing and removing chips at a huge rate after 30 years.”
And it’s that longevity that Correa sees as another major benefit for its end users.
“Once their return on investment has been achieved our machines will give 20-30 years of entirely profitable service and bigger margins. There may be cheaper machines available but if they only perform well for one or two years it’s wasted investment,” Mr García notes.
Naturally, providing so much capability and options for each machine means prices can vary greatly, even if they are on the same model or platform, but this is all part of the maximum added value Correa feels it offers customers to help them remain competitive.
That also includes further automation and Industry 4.0 features that are already being incorporated. The company is also investing in expanding its own manufacturing capacity in Burgos encompassing all its advances and to showcase to customers what can be achieved with the latest manufacturing technology available.
“We make general capability machines because they are used across so many different sectors but they are getting more and more complex because that’s what our customers require,” Mr García affirms.
“Ultimately all our products and services are aimed at optimising the return on investment our customers make and maximising their success. If a machine is properly designed from a mechanical perspective, you provide accuracy and reliability not just for the first year, but for the lifetime of that machine.”