The technicalities of success

Technology alone does not guarantee laser welding perfection – good relationships and leadership are just as critical. David Havrilla* writes.

SOME of the keys for success in laser welding may surprise you, especially if you are an engineer or scientist. In the world of high technology, it’s very tempting to reduce the success of a manufacturing process down to a keen understanding of a few basic technical principles.

In the realm of laser welding, those few principles might involve laser physics, metallurgy, tooling/fixturing, weld process parameters and DOE’s, part strength testing, and the like.

Certainly a thorough grasp of these topics is critical to the success of any laser welding project, but there are other matters that can’t be calculated or graphed that are every bit as important. What follows is an endeavour to re-emphasise a couple of the important technical matters, as well as to touch on a few of the important, but sometimes overshadowed, managerial and relational keys to success.

Designing components for laser welding

Designing component assemblies for laser welding is absolutely critical for successful implementation – not just from a weldability perspective, but also from an economic point of view.

A few of the important considerations are as follows:

n Reduce component weight and cost by reducing flange widths and gage thickness;

n Reduce component as-welded distortion due to the high energy density / low heat input laser welding process;

n Elimination of secondary processes such as grinding, finishing and straightening by taking advantage of the low heat input and high weld seam aesthetics and;

n Pursue unique styling of components enabled by laser welding and/or laser brazing (e.g. laser brazing of automotive ditch joint thereby eliminating sealing and the use of plastic molding to “fill-in” the ditch).

Maximising laser beam on time

Maximising laser beam on time (i.e. welding time) is key to cost justification. It’s obvious that every minute the laser is waiting for parts, the laser welding system is literally in a holding pattern, which leaves the potential for increased revenue also on hold. The key here is to keep the “beam on part” as close to 100% as possible. There are at least two ways of addressing this issue.

First, beam sharing can be utilised. Basically what this means is that the beam is shared between two or more production work stations – so while parts are being unloaded & re-loaded at one station, welding is occurring at a secondary station.

Another way to increase beam on time is to utilise a welding process that has become known as “remote welding”. This process uses relatively long focusing optic (hence “remote”) with beam manipulation at the work piece accomplished via scanning mirror(s).

Early involvement from production personnel

Involving the using plant early in the process is one of the basic keys to success. It’s the key to ownership, technology transfer and acceptance.

Manufacturing engineers, whether at a remote location or in the front offices of the using plant, would do well to involve key individuals from the production staff at the onset of any manufacturing project. This is not simply a pragmatic necessity to gain philosophical unity, the many years of combined experience from those who make manufacturing systems produce parts day in and day out is the primary fruit of this effort.

Selecting a laser partner for success

The race toward higher power, better beam quality and lower prices has existed in the realm of laser technology since the very first days. However, one absolutely critical objective is to achieve these three attributes in a product that is industrially robust, flexible and field serviceable by factory maintenance personnel.

Here are some points to examine carefully when selecting any industrial laser:

n Does the laser manufacturer have an excellent and proven reputation? Have they demonstrated a history of successful new product launches? Are their products known to be reliable and industrially proven? Do they have excellent global service and spares support?

n What is the extent of vertical integration of the laser supplier? This is critical, because the industrial customer needs minimum risk – from the laser source, all the way to the workpiece. If, for example, a beam delivery fiber fails on a routine basis, this is just as costly to production as a problem within the laser source.

On the controls side, for example, laser power feedback control is essential to insure that the delivered power is equal to the programmed and expected laser power.

This is significant because laser power (if not monitored and controlled) fluctuates with cooling water temperature, back reflections, diode failures (in the case of diode pumped lasers). On the diagnostics side, the appropriate quantity and type of sensors are needed – so that real values of voltage, current, temperature, pressure, flow rate, etc. can be seen in order to facilitate diagnosis and repair.

When you consider the keys to success of any laser welding manufacturing system, there are some things that cannot be directly measured or calculated that are every bit as critical as those things that can be. However, technical perfection alone does not guarantee success. The leadership and relational topics that were presented are just as critical.

*David Havrilla, is the Product Manager – High Power Lasers at Trumpf Inc. For further information on laser welding, contact Headland Machinery on 03 9244 3500 or visit the website at www.headland.com.au.