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Thursday, 6 April 2017

Renishaw technology helps Breton calibrate its in-house machinery

Switching from processing stone materials to metals demands a significant increase in precision. Now Breton uses laser interferometers, rotary axis calibrators, ballbar systems and touch-trigger probes thanks to Renishaw technology. As a result, today, Breton’s range of high-speed, five-axis CNC machining centres are among the world’s most advanced.

Calibrate accuracy
Based in Castello di Godego, Italy, Breton has come a long way since its foundation in 1963. Focussing initially on designing and building machinery to process natural stone, the company soon transitioned into also producing complete systems for the manufacture of composite stone (7% polyester content). This innovative material had, in fact, been invented by Breton and proved the backbone of its growing business for many years.

A moment in the rotary axis calibration process
The 1980s saw Breton begin building CNC machinery for processing marble, granite and composite stone slabs aimed at the kitchen worktop and bathroom sector; this particular era also included the arrival of the company’s first five-axis systems. A decade down the line and Breton began to diversify its expertise into the production of high-speed CNC machining centres for the metal-cutting industry. Renishaw technology helped Breton ensure the quality and precision of its in-house production machinery, and its fully assembled machine tools.

Talking about accuracy
Samuele Salvalaggio, Sales Engineering Office, explains how Breton’s own production machines, as well as those the company builds, follow practically the same control and calibration procedures.
You cannot produce precision machinery if the components are not produced using precision machinery,” he stated. “Our quality control methodology essentially encompasses three phases: linearity control, the checking of axes, and overall control of kinematics, which are all carried out using Renishaw products.”

Ballbar system calibration technology
Once a machine is assembled, a XL-80 laser calibration system is used to test the positioning, linearity and the angular errors of the machine tool. These controls are carried out on all the machine tools produced by Breton. This process is also performed annually on all in-house production machinery and repeated on the rare occasion that deviations are recorded. The company opted for the XL-80 after experiencing difficulties using other systems on axes over 4 metres, a problem which is non-existent with the XL-80.

XL-80 laser calibration system

Machine axes are also the subject of strict quality control routines facilitated by using a Renishaw QC20-W ballbar system. The QC20-W is used to quantify the squareness between each linear axis and to check a machine tool’s fundamental performance via a quick check.
Once staff in the maintenance division, who already used a ballbar system for their periodic checks, showed others how easy to use and accurate the system was, it became a standard tool in every part of the company needing calibration controls.

Among other things, this check is also the first one conducted when customers request technical support for machines installed in the field. At Breton’s 40,000 m2 premises, checking the three linear axes of in-house production machining centres is also a straightforward operational routine. In just 20 minutes the operator can check the condition of the machine and prevent possible manufacturing errors. The ballbar system is now used internally to calibrate the production machines and externally for technical support, particularly when a customer suffers a machine collision.

At Breton, which today employs around 700 people, core business remains the stone processing sector, and here too, despite the fact that precision levels are lower, the benefits of calibration are now fully appreciated. All of Breton’s machines for natural/compound stone processing undergo calibration routines which guarantee their optimum operation.

For more information about Breton's 5-axis machining centers, please write to

Many thanks to Renishaw for the provided case study document. 

Wednesday, 29 March 2017

Breton automatic countersink solution for aerospace and automotive industry

Countersink? No problem!

The use of rivets is 
one of the most common standards for the permanent assembly of structural parts in aerospace and automotive sectors.
For reference only, the image on the right shows a typical distribution of different rivet types in a famous aircraft with a very recent design.
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Despite some minor limitations, this system offers useful advantages in the assembly process:
  • Rivets are cheap
  • The procedure is easy and fast
  • They are available in many different types covering any need
  • There is a long history and experience in their use leading to a good reliability guarantee 
  • Compared to other permanent fixations, they can be disassembled quite easily with specific tools 
  • They allow a calculated residual flexibility of the assembly 
  • They allow easy and fast repair even on the field                   

When rivets are used to assemble the external layers on the supporting structures, they need to fulfill another very important role because the resulting assembly is directly exposed to the airflow: the final surface must be as smooth as possible in order not to affect the aerodynamic performances.
This specific need is very common in the aeronautic and aerospace field and all designers solve it by selecting rivets with countersunk head.

It becomes therefore evident the need of an accurate hole on the surface prepared with a countersink: the rivet head needs to be hidden below or in line with the external surface profile.

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Just to reinforce the importance of the final surface quality the rivet head flush requirement is directly expressed on the assembly  drawing  through specific symbols (like a welded joint) and described in detail through dedicated quality procedures involving, very often, also a source qualification need.

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In order to better understand how important is to respect 
the perfect surface continuity we can consider that, on 
some aerodynamic very demanding design, the aircraft  performances are so sensitive that just the surface cleaning has a perceivable impact on the overall performances.

The standard way of performing the rivet assembly is manual with specific tools that allow improving the reliability of the process.
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Generally, the structural parts and the sheet metal pieces are NC machined and prepared with smaller holes in order to guide the manual tools used to create the final hole and countersink prior to assemble the rivet.

Sometimes only one of the two element to be assembled is pre-drilled in order to allow compensation of assembly misalignments; in this case, operator’s job become even more complex and sensitive, thus requiring higher manual skills.

There are a few reasons for the aircraft manufacturer to choose this way rather than finishing the hole and the countersink on the NC machine:
  • The hole and the countersink must be perfectly perpendicular to the surface
  • The countersink depth need to respect quite a tight tolerance in order to avoid rivet head to be above the surface. We must consider that the material  thickness tolerance can be easily equal or even higher than the countersink one
  • The position tolerance need to be very tight as well in order to guarantee that the two parts will match during the assembly
  • Even if in a modern design all the parts are 3D modelled (it’s not the same in an older aircraft) the production processes of a structural part and a sheet metal one do not guarantee the same level of precision 
  • The sheet metal is a flexible piece and it’s  very difficult to create a fixture that maintain the overall surface in the 3D model  theoretical position
All these reasons made the manual rivetting process the more convenient one, leaving to an expert operator the responsibility to recover all the previous processes misalignments.         
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Everything said above is valid even if the sheet metal is classical aluminum or composite based. In this second case, some other points must be considered:
  • The dust produced is very dangerous for the operator's health
  • The material cut is very critical and need better control of the cutting  parameters
  • The material surface control is even more complex
Until the business remains focused on small quantities and the market is ready to reward the “hand-made”, and the consequent high value added, as a “plus”, it’s possible to sustain the manual production process with respect to massive  production competitors.

How does all this match with NC 5 axis machining?
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When the scenario changes to big numbers (typical of the civil market) with reduced prices and margins, the only solutionthe only solution to stay competitive is the process standardization   and automation, so the aerospace industry needs to find a partner who can help it achieving critical goals.                              

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On the market, it is possible to find solutions that substitute the operator job with a quite complex machine that request to introduce the full assembly jig into the machine in order to drill and rivet the components replicating the operator’s gestures.

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This strategy is very expensive, requesting a huge space allocation and presenting many times issues due to aircraft structures accessibility limitations.

Breton is following a different way, allowing to save the huge amount of money necessary for the previous type of investment and keeping the maximum flexibility to apply the solution to any type of component.
Breton has developed specific machines and several solutions to support this type of challenge and has also a very strong and experienced process development team available to support customers before and after the integration of a fully comprehensive solution.

The only ground condition is the availability of a 3D part model, Breton takes care of anything else.
For each of the previous points supporting the benefits of a manual riveting process, Breton has a specific automatic solution leaving the final fastening to the operator but with the hole and countersink already prepared in the correct position, shape and  depth:
  • Position precision is not an issue for any Breton equipment that is designed  to  achieve  the  best  5-axis  tolerance  on  the market.
  • A specific automatic probing head is capable to calculate the real surface position in respect to that of the 3D model and calculate the corrections in order to recover depth of cut and surface perpendicularity
  • The machine position is automatically modified without any operator assistance before drilling the hole and   countersink
  • With this solution the fixture only needs to keep the piece well fixed but it can leave to the machine probing capability the real shape calculation
  • The composite dust issue is solved avoiding the operator to be exposed to it during the material cutting
  • The composite integrity is guaranteed using a special developed solution that avoids any contamination and completely removes any dust
  • All the cutting parameters can be controlled much better than in a manual mode
  • The software is also capable to monitor the surface stability during the cutting operation and can be programmed to react in different ways according  to  the material responsiveness.
  • The structural part can be machined on the same trimming machine in order  to have the same level of precision. This way is the first step to guarantee a good assembly performance.

The core of Breton automatic countersink solution is the special probing head and compensating software.
They have both been designed at Breton’s and patented due to their specific and unique capabilities on the market.

The special probing head is stored in a specific holding device on the machine, protected and located outside the working area; when necessary, the machine automatically picks it up, while keeping  the tool change capability monitored through a specific application in order to avoid any collision with the device.

The system is composed of three mechanical transducers managed by a specifically developed NC control application in order to acquire the true position and orientation of the piece surface around the hole to be done.

The drilling program is a standard one where the machining cycle is substituted with the Breton routine to activate the countersinking head.
The typical drilling process follows these  steps:
  • The machine collects the special probing device
  • The machine picks up and measures the cutting tool (using a specific   Breton routine)
  • The machine sets up the probing device on a reference gauge integrated in the machine (using a specific     Breton routine)
  • The machine probes the surface in the theoretical position and orientation
  • The real position and orientation is recalculated by Breton software
  • Depending on the surface type and scratch sensibility, the machine position and orientation are corrected by either keeping the probes in contact with the piece or retracting the machine from it (average time of the full probing and position adjustment is 6 seconds)
  • The drilling and countersinking cutter proceeds along the real hole axis until the probes detect the correct depth of cut (this time depends on the type of material, layer depth, type of cutter, etc..). The system is capable to respect a depth tolerance of +- 0.03 mm on a stable surface (or +- 0.06 mm if the surface is not perfectly supported and fixed by the fixture)

The machine head is also equipped with a special dust extraction hood in order to collect all the dust generated by the drilling process.
There is no limitation in spindle performances as all the probing systems are static and connected to the head flange without any external   wire.

Depending on the material type, the head can supply compressed air, spray oil mist or pressurized coolant up to 40 Bar as the probing devices are fully sealed.

The following pictures explain the capability of the special head comparing the results of countersinking with and without the Breton solution:

This sequence is useful to understand better how the full process is working:

The system can be installed on any Breton machine giving the customer huge advantages compared to the manual process, spending just a small portion of the investment requested by more sophisticated solutions. 

(Breton is not yet assembling the rivets…).

Summarizing the points of strength of Breton solution:
  • One machine to trim, drill and countersinking
  • Precise process control
  • Small investments in a machine accessory
Since one of Breton’s major points of strength is its capability to hear the customer’s requirements, we are working to further improve this system reviewing the design and testing a contactless   solution.

Test Case: Composite panel
Machine type: Eagle 1500 2T K80 
(5 axis overhead  gantry machine) 

Machine size:  
X=8000 mm
Y=4000 mm
Z=1500 mm

Machine accuracy:  
X=+-0.02 mm 
Y= mm
Z= mm

Number of countersinks on each side of the part: 55
Countersink depth: 0,31 ± 0,08 mm 
Process stability achieved: Cp 1,34
Cpk (lower) 1,14

The following graph shows how the system recovers the hole surface perpendicularity starting from the theoretical one, measuring the real surface orientation (red lines in the graph), correcting the head A and C axis and checking the final result (green lines in the graph).

After this first phase, the system starts monitoring the countersink depth comparing the probes data with the target   values.
The final result, achieved on a composite part not perfectly stable on the fixture, is shown in the process control chart here   below:


The process stability is very nice giving a big safety margin. The customer chose to further increase the safety margin moving the average countersink depth in the lower tolerance direction (as show by the Cpk value).

For more information please write to

Thank you for the attention and best regards.

Sergio Prior

Tuesday, 21 February 2017

Launch of the new Renault F1: Breton is a technical partner

Good morning everybody,

Breton, technical partner of Renault Sport Formula One Team, invites you to watch the launch of R.S.17, the new car that will compete in the 2017 Formula 1 World Championship.

Today at 15:30 (14.30 UK).

Here you can follow the live streaming

Good show at all!

Well, that’s all for today. 
Sergio Prior

Wednesday, 7 December 2016

“We've shifted gear”

The arrival of a Breton Eagle in SCA's workshop in Gessate (Milan) not only solved a host of operational problems, it also allowed the company to approach sectors and materials that were hitherto excluded.
(From: Meccanica&Automazione)

Founded almost fifty years ago as specialised manufacturer of foundry moulds, SCA is currently headed by the third generation of the proprietor family and, in a sense, it's experiencing the third “revolution” or – more accurately – conscious evolution of its operating activities.
The company was incorporated in 1970 by Domenico Scalzo and is currently headed by his grandson assisted by the second generation of the family.
The Breton Eagle of SCA 
Like many companies set up in the 1970s, the business started in cramped premises and worked with all kinds of industrial sectors: from moulds for motorcycle cylinder heads and interior light fixtures, to the initial production of parts for the Italian bottling industry.

In fact, it was a customer in the bottling sector that provided the basis for SCA's first turning point. With the customer in question, which remains a point of reference for SCA, the company began a journey into the world of industrial automation that enabled it to build its technological expertise until becoming a qualified supplier of parts for bottling plants (glass and plastic).

Rather than resting on its laurels and running the risk of supplying a single customer, over the years SCA maintained or developed a series of opportunities in several sectors that differed widely from the automatic machinery field, until it gradually left its origins in foundry mould-making in the past.

Competing in multiple sectors
This direction change led SCA to work with numerous industrial sectors, especially those calling for the ability to work with different materials with high levels of precision and the maximum operational flexibility.

From food and chemicals to pharmaceuticals and cosmetics, the marine and aeronautical industry, and also construction of large size components for theatrical stage sets. These various different areas of activity called for the ability to work with a large range of different materials, which is why SCA's machining shop today is equipped with machines for plastics, metals, and even, marginally, woodworking machines. The diverse range of applications calls for specific machines for each material type, each capable of producing optimal results.

Alessio Restelli explains “Several years ago we decided to focus our investments on machine tools for metals and alloys. That's why we decided to purchase a large size machining centre for specific work processes on workpieces in aluminium and lightweight alloys. Unfortunately however, we soon discovered that the machine we had identified was unable to cope with the work in our production programme. We were looking for a machining centre with large working dimensions, capable of processing different materials and providing absolute reliability. Above all, we were seeking a definitive solution to the problems we had encountered. And the need was all the more pressing because we were very keen to enter new business sectors and consolidate our capital equipment”.

SCA found the answer by embarking on a series of analyses and checks, trawling through the information available on the various companies and products on the market.
“We soon realised that our requirements in terms of equipment and solutions were a very good fit with the machine tools produced by Breton which, thanks to its long experience in building machines for a range of materials from stone to metal, was the ideal candidate to provide the tranquillity we were looking for. This saw the start of a period of negotiation that went extremely smoothly, especially when we went to visit Breton at the company's headquarters, near Treviso".

Breton Eagle

A paradigm of rationality and organisational efficiency.”
The final choice fell on the Eagle, a gantry-type machining centre offering exceptionally generous working dimensions: 4200 mm (X) x 3000 mm (Y) axis x 1500 mm (Z). We then requested that these characteristics be integrated with a separate lath so we could turn workpieces of up to two metres in length, using the Eagle head (shown in the attached photos) as a turning-milling device.

Restelli explains – “Our Eagle is not merely an extremely efficient machine able to produce work of the utmost quality and with exceptional dimensional precision, it also allowed us to benefit from the positive experience of working with the Breton team that were looking after our interests. Apart from absolute respect of precision and times, we were also impressed by the creation of a valuable collaborative relationship that was built on our combined efforts to find the best possible solution to our needs".

"For sure, the machine tool in question is extremely valuable, but the whole process was also accompanied by a truly exceptional the level of customer care and assistance. We quickly realised that the people at Breton were far more than expert engineers. In some cases the relationships we developed morphed beyond the professional realm and became more akin to actual friendship.

We started to perceive Breton's people as an integral part of our own team - a development that brought substantial value to the whole process. For companies working in our sector it's extremely important to be able to rely on a partner that allows us to focus on our core business, without having to lose sleep about possible breakdowns, problems, or the inability to achieve the quality levels we need. Setting aside the problems and focusing on the job means that we can relax and get on with what we do best. And that's just as important to us as the very air we breathe”.

Breton Eagle, range for resins, composites and alloys

Eagle is fully articulated range of travelling bridge gantry machining centres dedicated to the world of composite materials, resins and aluminium. These machining centres are perfect for fast, high precision 5-axis machining of 5 faces of the workpiece with a single set-up operation.

The various configurations of EAGLE machining centres for composite materials make it possible to perform even the most complex tasks with the maximum flexibility and operating efficiency, with working dimensions from 2,000x2,500x1,000 mm up to 10,500x5,000x2,500 mm and beyond.

The machine offers the maximum production flexibility thanks to the possibility of configuring the work area, which can be optimized for machining single parts or pendulum machining operations. Our job is further facilitated by the optimal visibility of the work area and the double front and rear access doors, allowing easy loading and unloading procedures, tooling set-up and monitoring of machining operations.

Would you like to find out more about the Breton Eagle? For INFO and inquiries write to

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