Step forward Sandvik Teeness in Trondheim, Norway. The team was chosen for its reputation as a market leader in the in the development and production of boring bars that goes back to the 1960s.

If you are a manufacturer of aerospace components, aluminium boats, bull bars, truck body parts, or if you are fabricating mild steel or aluminium sheet you need an Australian designed and manufactured Multicam CNC cutting machine. Machining procedures such as routing (milling), drilling, boring, engraving and modelling are all handled with ease. Whether you need to machine extrusions, solid block product for 3D molds or flat sheet and plate we have a system that will deliver perfect results with the versatility to handle all your profile cutting requirements.

The tool was run with a maximum allowed overhang of 10-times the diameter (10 x D), recommended to minimise vibrations and obtain the best possible stability and accuracy. Sandvik Coromant’s Silent ToolsTM boring bars, so-called because they operate with minimal vibrations, are in general used at long tool overhangs and a rigid clamping is very important. Cylindrical boring bars should always be clamped in split sleeve holder with a minimum clamping length of 4 x bar diameter.

“The world’s largest boring bar remains testament to Sandvik Coromant's unwavering commitment to innovation and precision and machining applications,” said Faber.

The machine tools specialist Sandvik Coromant has etched its name in history as an innovator in precision engineering, by developing the world's largest boring bar. Measuring almost 11,000mm (11 m) in length and 600mm in diameter, this engineering behemoth has been developed specifically to meet the machining requirements of Häkkinen Group Jyväskylä unit, a Finnish engineering company.

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Jaroslav Šuga, global account manager at Sandvik Slovakia added: “There were regular meetings with the Sandvik Teeness production team about the bar’s delivery time and all details concerning manipulation, transport and logistics. Success was possible because we worked together with ŠMT’s designers, technologists, the production team in Norway and all people involved in the sales process.

The bar is made of steel and contains a component called a "damper" made of heavy metal. A damper is a device used to reduce or absorb vibrations, rarely found in machinery or structures, and clamped in special rubber rings.

Multicam CNC machines are ideal for manufacturers in sectors such as aerospace, marine, and automotive. Whether you are producing aluminium boats, bull bars, truck body parts, or fabricating mild steel and aluminium sheets, our tools can efficiently handle various machining processes, including routing, drilling, boring, engraving, and modelling.

To this end, ŠMT turned to Sandvik Coromant CZ, also based in the Czech Republic, to ask if it could support with the development of the huge bar.

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The cutting data was based on initial recommendations generated by the CoroPlus® Tool Guide software platform, which were amended during the tests. For the roughing application, the bar was run every time with a cutting speed (vc) of 100 m/min and feed-per-revolution (fn) of 0.4 mm/rev. The load on a boring bar is mainly dependent on the depth of cut (ap), the feed and the workpiece material. It is essential to ensure a sufficient ap and fn to avoid vibration during cutting. An ap and fn which is too high can cause vibration through tool deflection.

To explore our range of CNC tooling and accessories for effective metal processing, request a quote tailored to your specific requirements.

ŠMT had other stringent requirements for the bar: its customer, Häkkinen Group Jyväskylä unit, needed a tool that would integrate seamlessly with its existing machinery while pushing the boundaries of turning operations. It was also essential that the new bar be compatible for use in ŠMT’s huge lathe.

The gargantuan lathe tool is going to be used to produce precise metal components for a range of sectors including offshore oil and gas, power transmission and renewable energy.

The required tool was a boring bar, used in machining operations to enlarge and refine the diameter of an existing hole in a workpiece. The holes made by a boring bar are more precise, accurate and smooth than those made by drilling, which may produce rougher holes.

In the finishing and also profile applications, the bar was run at a vc of 110 m/min and ap of 0.5mm ever time. The fn was adjusted, and 0.25 was found to be the optimal and recommended setting, giving a roughness average (Ra) of 3.4.

The A2MC controller in our CNC machines delivers smooth and synchronised movement across all axes. This technology enhances edge finishes, reduces cycle times, and extends tool life.

Sandvik Teeness’ specialists conducted crucial frequency measurements on-site to assess the effectiveness of the dampening adapter integrated within the bar. The bar was put to work in a large CNC lathe and tested multiple times in three applications — roughing, finishing and profiling — each time with different cutting data.

The open architecture of Multicam CNC machines allows compatibility with industry-standard software. Commonly used programmes like AutoCAD, Enroute, Fusion360, SolidCAM, CAMworks, JetCAM, Visual Mill, and Rhino integrate seamlessly with our machines.

“Based on the test results, Sandvik Coromant’s specialists were able to recommend cutting data parameters and inserts to ŠMT,” explained Faber.

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Häkkinen Group Jyväskylä unit approached its partner ŠMT — formerly Skoda Machine Tool — based in the Czech Rublic, one of the world’s leading producers of high-precision horizontal boring and milling machines, horizontal lathes and more. It was clear that ŠMT would need to enlist the services of a machine tooling specialist that could supply a boring bar with the extraordinary dimensions needed to accommodate the demands of such a unique project.

“The tool holder has proven especially useful in multi-task machines,” said Faber. “It enables assembling of tools with different lengths and design characteristics regardless of the machine interface. The Coromant Capto also meets Häkkinen Group Jyväskylä unit’s requirement for a boring bar that can be useable in a diverse range of industrial setups.”

Excessive vibrations can lead to inaccuracies, tool wear and compromised workpiece integrity — which were concerns given the huge scale of Häkkinen Group Jyväskylä unit’s machining operation. Instead, by minimising vibrations, the boring bar maintains stable and controlled cutting conditions, which results in higher productivity, extended tool life and superior surface finishes.

“Sandvik Coromant is renowned as a producer of boring bars, particularly bars with anti-vibrational qualities,” explained Vaclav Faber, project engineer at Sandvik Coromant CZ. “Reducing vibrations in a boring bar is crucial because it ensures precision and surface finish quality in machining operations.”

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Our systems are designed to machine various forms, including extrusions, solid blocks for 3D moulds, and flat sheets and plates. This versatility ensures that you achieve precise results for all your CNC steel cutting and profile cutting requirements.

Multicam provides a complete solution for CNC routing, offering a broad range of tooling and accessories tailored for processing aluminium and composite materials effectively.

Another crucial feature of the bar is the Coromant Capto tool holder affixed to in front of the bar, which would hold the cutting inserts needed to machine the workpiece. The Coromant Capto is designed to reduce set-up and tool change times for significantly increased machine utilisation, and to support stable and reliable machining.

At Multicam we offer a complete metal cutting solution for your CNC router by providing access to a comprehensive range of CNC tooling and accessories that makes processing aluminium and composite materials easy. Our advanced A2MC controller delivers smooth, fast and perfectly synchronised movement in all axes simultaneously which translates to better edge finishes, reduced cycle times and increased tool life. The open architecture of Multicam CNC routing machines and profile cutters means that you are free to utilise any industry standard software to create programs for the machine. Packages such as AutoCAD, Enroute, SolidCAM, CAMworks, JetCAM, Visual Mill and Rhino, to name a few, are all used extensively by our customers with their machines.

Non-ferrous metal machining is a key advantage of Multicam CNC machines and profile cutters. Our metal CNC machines are used by a variety of manufacturing businesses needing components made from aluminium, brass, copper, and metal composites.

However, the diameter and length of a boring bar is determined by the dimensions of the workpiece itself. It is recommended to select the largest possible bar diameter for an application to achieve the best possible stability. Put simply, the application required a boring bar of unprecedented dimensions. The large size would be essential to enable deep and precise internal turning operations, a task beyond the capability of standard-sized bars.

Sandvik Coromant has developed a boring bar that’s not only remarkable for its size, but is also an invaluable asset for Häkkinen Group Jyväskylä unit, in whose workshop it is now being used to precision machine components for diverse sectors. Going forward, and impressed by the world’s largest boring bar, ŠMT plans to invest in further — albeit slightly smaller — boring bars from Sandvik Coromant for the machining of slightly smaller components.

For these reasons, the ap was adjusted for testing purposes. The boring bar showed signed of vibration at an ap of 5.6mm and limited performance at 4.5mm but, in the end, 3.5mm was found to be the recommended depth of cut.

When it initially approached Sandvik Coromant, Häkkinen Group Jyväskylä unit had an unusual set of specifications. It needed a tool capable of machining a specific type of component with critical dimensions. Although the type of component was not specified — due to confidentiality agreements — it was especially large, measuring 800 mm in diameter by 12,000mm  (12 m) in length, and would be machined from both sides.