Laser Maintenance – Rising Costs

January 2013


Laser maintenance and boosting cutting efficiencies can add profit to your bottom line

Every year businesses are faced with rising costs, and this year it’s definitely not going to change.

Running your laser as efficiently as possible along with productive material handling can make a big impact on saving costs. Here are some suggestions.

To compete, company owners have the opinion that they have to be better equipped with the latest equipment than their competitors. In some cases, they’re correct. Some of the new laser technologies available today are amazing.

However, if a company has internal process problems, they will get magnified by the cost of downtime when making payments on the new equipment.

Everyday I travel from one company to another and find that the laser is always in the early areas of the production line. If you’re going to improve the way you do business, you need to start at the beginning of your production process.

A laser isn’t the cheapest piece of equipment to operate. However, it does have great earning potential. Those of you who currently own one know that small problems can lead to expensive repairs if left unattended.

Laser inefficiencies

As mentioned, everyday I’m at a different company servicing lasers, and I’m amazed at how each company processes material differently. I’ve seen bad material handling efficiencies along with operators who neglect to make the simplest adjustments to their cutting conditions and accept poor edge quality on parts. Then they get out the grinders and waste time and money on grinding disks to correct unacceptable edges.

I see lasers running far below their cutting capabilities, meaning the company is losing money on these parts. I find machines so badly maintained that it’s truly amazing that the machine is capable of running parts.

Recently, one company that runs three laser three shifts per day, six days a week had a laser breakdown. Their call to me requesting service was a sheer cry of panic with the comments, “We can’t afford a minute of downtime, we need you right now.”

When I entered the facility, I observed all three machines idle. Employees and management greeted me at the door commenting, “Thank God you’re here. We’re so far behind on production, we’re going to work Sundays to catch up on the backlog.”

The comments then proceeded to, “How long will it take to repair the machine?“ I definitely sympathized with their concerns and comments, but I needed to look a bit deeper to find the true problem.

Finding the problem

Most lasers are capable of recording how many hours the laser has been ON and how many hours the laser beam has been ON. From these two numbers, I can calculate the machine and operator’s efficiencies.

The company was amazed when we did the calculations and found that they were only 26 percent efficient, when they thought they were doing everything possible to keep the machines loaded and cutting. Now that I had their attention and got their machine running again, management set their focus on improving uptime.

Because change never comes easy, the first couple of weeks were difficult as we pointed out ways to improve their processes. After two months, we were finally moving our number up to 68 percent and went from three shifts, six days per week to two shifts, five days per week even though the work load hadn’t changed. I have to admit that 68 percent is not a great number, but we were finally moving in the right direction and every bit of savings adds to the bottom line.

Most problems boil down to some fundamental operating processes:
either the lack of supervision or no one is monitoring the laser’s cutting processes. You need to verify your machines are running at their capabilities, and if they aren’t, find out why. You need to also look at the larger picture to determine why you’re losing or making money.

Data gathering

Gathering data is the easiest method to make intelligent choices. Keep records by shift on efficiencies, downtime and laser cutting feed rates compared to the quoted part feed rates. Also, verify if operators are using machine overrides to slow down the machine.

Document how well the machine is running by benchmarking how consistent the power level is daily. A drop in power will result in a drop in your cutting speed, or if the focusing lens is getting dirty you could possibly shorten its life if not cleaned in a timely manner.

Determine the true cost of any lack of maintenance with regards to premature part failures or downtime waiting for replacement parts or the added cost of parts shipped overnight. Determine if training is required for personnel. Test the operators’ knowledge or your maintenance personnel’s ability to support your machine.

Keep records of how often gas bottles are changed. If you keep records, you can determine if you have leaks.

Lens cleaning

Another commonly overlooked item is the focusing lens. Every laser has them. But does it get cleaned as often as it should?

Let’s start with the pros: One school of thought states, “Only clean your lens when it’s dirty.” Doing so will minimize the chance of scratching the thin coating of thorium fluoride on the surface. Scratches will increase light absorption and scatter it. Additionally, cleaning optics takes time away from the production schedule.

On the opposing side, failing to periodically inspect the lens could have a multitude of unwanted and potentially costly results. Two conditions can exist: a visibly dirty lens or a lens with a hydrocarbon film not seen by the naked eye. Although you might not see it, you can smell the difference. A clean lens will have no odor while a contaminated lens may take on an odor described as rotten eggs with the intensity depending on the level of contamination.

Regardless of the contamination type, it will cause thermal lensing. This is a condition where the lens starts absorbing more of the precious power we pay extra for when buying our laser systems. The result is a focal point that drifts due to the temperature dependent index of refraction, ultimately causing dross on our parts.

In response to the poor cut that this will cause, the operator will adjust cutting parameters in a futile effort to correct the problem. Unfortunately, he will continue to adjust the laser trying to compensate for a forever-changing focal point all the while moving further away from good cutting parameters.

 As the operator’s frustration level increases, the manufacturer will get sub-standard parts and/or extra labor costs to correct them. While struggling to get acceptable parts, production levels are reduced and proven cutting parameters lost. Once the operator cleans or replaces the lens, the struggle is only half over. Now the operator will have to adjust parameter settings to get them back to their original position, continuing the time lost through reduced production.

Lens inspection should be one of the first things an operator checks when there are problems with the cut quality. In fact, a polarized stress tester to check for any lens damage should be used.

One of the factors in determining a lens inspection interval is the type of materials processed. This interval should be frequent enough to provide a consistent process to reduce your hourly costs.

If the lens is ignored long enough, it will stress and end in a catastrophic failure that will turn the ZnSe lens into a dangerous yellow powder. This powder is a serious health hazard requiring immediate evacuation of the area. Please refer to an optic manufacturer’s information on this such as Ophir Optic’s MSDS for a complete report.

Besides the health issue from a lens failure, a system will require extended downtime and costly repair to thoroughly clean the debris from the beam delivery guide and undoubtedly, components will need to be replaced in the cutting head.

Checking a lens is time well spent considering the alternative.

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