Product category:
CNC laser cutting and profiling machines
News Release from: Burrhart Machinery | Subject: Ophir lenses, nozzles and ceramics
Edited by the Manufacturingtalk Editorial
Team on 22 March 2005
Low-cost consumables improve NF edge
finish
Making a change to Ophir lenses, nozzles and ceramics, a non-ferrous sheet metal stockist can now supply finish-machined components at competitive prices to aircraft manufacturers.
In 1998, Blackburn-based Rolled Alloys was the first non-ferrous metal stockist in the UK to install a laser cutting machine a Bystronic 4020 to expand its supply of custom profiled, high accuracy, flat sheet metal parts Until then it had relied mainly on water jet cutting and plasma burning for thicker materials
This article was originally published on Manufacturingtalk on 10 Apr 2003 at 8.00am (UK)
Related stories
Punch press tool self-locks sheet metal joints
Punch press tool forms a self-locking joint at the edge of sheet metal components as part of the CNC machining cycle.
Semi-automatic unit sharpens punches accurately
A subcontract sheet metalworker has transformed a tedious, imprecise job into a fast, accurate process using a semi-automatic grinding machine for resharpening turret punch press tooling.
For two years, Rolled Alloys was unaware of the existence of independent suppliers of consumables for the 3kW CO2 laser but in 2000 switched to Ophir lenses, nozzles and ceramics supplied exclusively by Burrhart Machinery.
The improvement in edge finish was immediate, even of aluminium components which many companies will not even attempt to cut by laser.
It has enabled Rolled Alloys to supply finish-machined components at competitive prices to a number of aircraft manufacturers on a job-specific basis.
Further reading
Nozzle reduces CO2 laser profiler running costs
Patented nozzles for CO2 laser profilers optimise gas consumption to reduce running costs and protect the lens from being spattered when breaking through the material being cut.
Forming tool guides improve productivity
GapMax forming tool guides increase productivity and reduce set-up time by eliminating the potential for collision between the tool and ram during tool changes
Roll-type strip feed mechanism fits many presses
Roll-type feed mechanism for increasing the productivity of coil-fed presses is claimed to be the smallest and least expensive electronic press feed available and fits many press makes.
No post-machining of oversize parts was needed to remove a heat-affected zone (HAZ) around the periphery, which can cause potentially disastrous edge micro cracking, as fast profiling at up to 8m/min minimises heat input to the material.
The resulting minimal HAZ has been exhaustively tested by customers, which have satisfied themselves that safety was not being compromised and that there were no other detrimental effects to the specific aircraft components, or their intended operation.
A number of aircraft flying today contain Rolled Alloys' sheet aluminium components that have been laser-profiled to size without any post finishing.
With the A380 superjumbo, Airbus has departed from tradition by introducing processes as the project develops in order to take advantage of new technologies, such as laser cutting to size which it is said to be considering, as it becomes clear that they are safe and can offer cost savings.
Said Barry Jackson, Technical Project Engineer at Rolled Alloys, "With all safety-critical applications, the quality of edge finish is paramount and in laser-cutting, the consumables play a big part.
Using Ophir products, in particular Black Magic meniscus* lenses, we were the first stockist to achieve burr-free edges when cutting Inconel and to receive approval from the aircraft industry for our laser-cut edge quality.
No preparation is now needed prior to welding, resulting in significant cost savings for fabricated assemblies." As 90 per cent of the work going through the Bystronic laser profiling machine is for the aerospace sector, the remainder being high temperature and corrosion resistant alloy components for the petrochemical industry, the importance to Rolled Alloys of achieving near-perfect edges cannot be over-stressed.
Jackson describes the modern laser cutting process as a highly precise production engineering tool, whereas he says many people still wrongly think of it as a jobbing shop facility.
Laser profiling consumables at the cutting end of the process fall into three categories - lenses, nozzles and ceramics - the performance of the first having the most significant impact.
Ophir lenses from Israel are either conventional yellow coated varieties or black, the latter being patented under the Black Magic Duralens brand name owing to the low-absorption coating (0.15 per cent versus the industry standard 0.2 per cent), which means that less heat is developed and the lenses last longer.
Moreover, as it is much harder than a yellow coating, it is better able to withstand back spatter through the nozzle and so cleaning intervals are longer.
Greater resistance to deformation minimises thermal lansing, a shifting of the laser beam which causes cutting inaccuracies.
Rolled Alloys' experience bears out these claims.
The yellow lens it used at the outset had to be changed monthly whereas a black lens lasts three times longer before it needs replacing, yet costs only 15 per cent more.
Further financial benefits accrue from higher production output as a result of fewer stoppages for lens cleaning or replacement.
Mr Jackson also commented that the black lens is less prone to the phenomenon of 'burning to a thickness', whereby a lens learns the thickness of the material it cuts most frequently and 'wears in' so that gauge, becoming less efficient at cutting other thicknesses.
As a result, using black lenses provides more flexibility when scheduling a mix of work through the laser profiler and minimises changeovers between lenses of different thickness.
Furthermore, unlike a yellow lens, the black version is less prone to variations in humidity, avoiding inconsistent cutting performance on damp days.
As regards copper nozzles, Ophir's have a chrome coating, unlike the products that were used previously by Rolled Alloys.
Again, the advantages are far-reaching, especially when cutting exotic materials.
The chrome discourages spatter from sticking to the copper and causing electrical leakage between the nozzle and the work, which can result in Z plausibility error so the head does not recognise where it is in the vertical plane relative to the sheet being cut.
Profiling of aluminium also benefits from the use of these nozzles.
Additionally, the Israeli company offers a greater variety at lower cost than other suppliers, and diameters go down to 0.8 mm, allowing more precise cutting.
Less expensive also, by a factor of 25 per cent according to Jackson, are Ophir ceramics - the third consumable in the laser head that insulates the nozzle and allows it to earth against the plate when cutting.
The Israeli product is effective at resisting the formation of cracks in the ceramic which would allow moisture in, reducing the isolation properties and interfering with the profile tracking capability of the head.
Only non-ferrous material is cut by laser on the Blackburn site - mainly aluminium, titanium, Inconel and stainless steel - as cross contamination would occur if ferrous or other oxidising metals were to be processed as well.
It is mainly the thinner gauges that go onto the Bystronic, with 70 per cent of work under 3mm.
Anything over 8mm is cut on the water jet machine or the plasma burning facility.
General drawing tolerance for lasered components is +/-125 microns on dimensions, although +/-20 microns is routinely held.
Only flat parts are supplied, but Rolled Alloys prides itself in providing design input to customers' projects, for example unravelling a solid model in CATIA so that it can be finish machined in the flat to avoid expensive 3D machining after it has been pressed.
Automated nesting software from SigmaNest is used to maximise sheet utilisation.
Whilst in theory the use of Ophir consumables, notably Black Magic lenses, can result in faster laser profiling speeds and reduced consumption of assist gases, Jackson advises that in their works, axis speeds are deliberately limited to maximise profile accuracy and edge quality.
This is undoubtedly one of the reasons for the company receiving AS9100 certification as well as approvals from GEAE (General Electric Aircraft Engine), Rolls-Royce and Pratt and Whitney.
The company was also one of the first metal suppliers to achieve ISO 9001:2000 (* Note that a meniscus lens, as distinct from a plano-convex type, has one concave and one convex surface and directs the power of the laser beam at a smaller, more concentrated spot with reduced spherical aberration, resulting in more accurate cutting and more consistent, burr-free edges).
• Burrhart Machinery: contact details and other news
• Email this article to a colleague
• Register for the free Manufacturingtalk email newsletter
• Manufacturingtalk Home Page
Search the Pro-Talk network of sites
