A colleague once used a made-up story to explain a problem that will probably sound familiar to anyone who has worked around automated laser equipment.
A new laser system had been installed, tested, and accepted.
The system produced good parts during the factory acceptance test. It repeated those results after installation at the customer’s facility. The customer, machine builder, and system integrator agreed that the equipment met the established acceptance requirements.
Several months later, occasional process defects began to appear.
Production called maintenance. Maintenance called engineering. Engineering called the system integrator. Before long, everyone was asking the same question:
“Who owns this process now?”
Again, this is a made-up story. It is not a documented account of one particular installation. However, it illustrates a misunderstanding that can occur after almost any automated laser system enters production.
Once the equipment has been proven and formally accepted, the equipment manufacturer and system integrator remain responsible for their contractual obligations. These may include equipment performance, workmanship, warranty coverage, replacement parts, technical support, and any additional service agreements.
The continuing production process window, however, belongs primarily to the customer operating the equipment.
That does not mean the laser manufacturer or integrator should stop caring about the customer’s success. Good suppliers usually want to help diagnose problems, recommend maintenance, provide training, and support process improvements.
But after acceptance, many of the variables affecting the process are outside their direct control.
The customer controls the production material, operators, fixtures, maintenance practices, inspection procedures, recipes, replacement components, production schedule, and changes made to the product or process.
That makes continued ownership of the production process window an end-user responsibility.
What exactly is the process window?
When people talk about a laser process window, they sometimes mean a range of laser power and travel speed.
That is part of it, but the real process window is much larger.
I would describe it as:
The combination of material, equipment, tooling, motion, environmental, and process conditions that consistently produces an acceptable part.
Depending on the application, the process window may include:
- Laser power delivered to the workpiece
- Focal position and spot characteristics
- Travel speed, acceleration, path accuracy, and beam position
- Joint gap, part position, and fixture repeatability
- Material grade, thickness, coating, and surface condition
- Shielding- or process-gas type, flow, and delivery geometry
- Wire or powder feed rate
- Scanner, beam-shaping, or oscillation settings
- Part temperature and production duty cycle
- Protective-window condition
- Inspection and process-monitoring limits
ISO 15609-4, which addresses welding procedure specifications for laser beam welding, includes equipment, parent material, joint preparation, fixtures, tooling, welding technique, and other conditions as part of the procedure specification.[1]
ISO 15614-11 addresses the qualification of electron- and laser-beam welding procedures through procedure testing and establishes limits for the validity of a qualified procedure.[2]
In other words, the process is not simply:
2,000 watts at 30 millimeters per second.
It is closer to:
2,000 watts delivered through a known optical system, at a verified focal position, following a controlled path, on parts with defined material and fit-up conditions, using a maintained fixture and an established inspection method.
That is less convenient than relying on two or three machine settings, but it is much closer to what production actually depends on.
Acceptance proves that the system worked under agreed conditions
A well-planned factory acceptance test demonstrates that the machine and process can produce acceptable parts under a defined set of conditions.
A site acceptance test may further demonstrate that the equipment performs correctly after shipment, installation, and connection to the customer’s utilities and production environment.
Once those tests have been completed and the customer has formally accepted the equipment, the supplier has generally demonstrated what it agreed to deliver—subject, of course, to the terms of the purchase contract, warranty, and service agreements.
That demonstration is important, but it remains a point-in-time result.
The acceptance parts may have come from one material lot. The fixture may have been new. The protective window was probably clean. The equipment may have been operated by the application engineer who developed the process.
Production interruptions, shift changes, fixture wear, replacement components, new operators, maintenance activities, and normal material variation may not yet have occurred.
AWS C7.4/C7.4M addresses laser-welding process control, quality examination, equipment calibration and maintenance, approval of work, and operator qualification.[3] ISO 17662 separately addresses the calibration, verification, and validation of welding equipment used to control process variables.[4]
These documents support an important distinction:
Qualifying and accepting a process is different from maintaining that process in daily production.
A useful comparison comes from FDA process-validation guidance. Although the guidance applies to pharmaceutical manufacturing rather than laser processing, its lifecycle principle is useful.
It separates process qualification from continued process verification—the ongoing work required to confirm that a process remains in control during routine production.[5]
A laser process can be viewed in much the same practical way.
Acceptance confirms that the machine and demonstrated process met the agreed requirements. Continued process control belongs to the organization operating the equipment.
Acceptance also depends on the parts provided by the customer
There is another part of acceptance testing that can sometimes be overlooked.
The machine builder or integrator is responsible for supplying equipment that meets the agreed specification. However, the customer may also be responsible for providing parts, materials, drawings, tolerances, and inspection criteria that meet the requirements used to develop and demonstrate the process.
This can be especially difficult when the laser system is being built for a new product.
The machine may be new, but the customer’s product, stamping dies, forming tools, machining processes, welding fixtures, coatings, and incoming supply chain may also be new.
In that situation, the integrator may be asked to develop and prove a stable laser process using parts that are still changing.
Here is another made-up story to illustrate the problem.
A customer orders a laser-welding system for a newly designed assembly. The integrator develops a good process using prototype parts that have consistent joint location and acceptable fit-up.
When production-intent parts arrive for factory acceptance testing, the joint gap varies considerably from one assembly to another. Some parts sit correctly in the fixture, while others are distorted or have locating features that do not consistently match the drawing.
The laser follows the programmed path correctly. The source delivers the required power. The fixture clamps the assembly as designed.
However, the weld result is inconsistent because the joint itself is inconsistent.
The customer believes the machine should compensate for the variation. The integrator points out that the process was developed around the agreed joint geometry and fit-up requirements. Meanwhile, the customer’s product and tooling teams are still adjusting the manufacturing process used to produce the parts.
No one is necessarily acting in bad faith. It is simply difficult to prove a stable process when the input parts are not yet stable.
This is why acceptance planning should identify more than the required cycle time and number of test parts. It should also define:
- Who supplies the test material and components
- Whether the parts must be production-intent
- The required material grade, coating, and surface condition
- Joint-gap and fit-up limits
- Dimensional and locating tolerances
- Whether nonconforming parts may be excluded from acceptance results
- How representative parts will be inspected before testing
- Who approves deviations from the agreed part specification
- What happens if suitable test parts are unavailable
- Whether additional development work caused by product changes is included in the original scope
A laser system should not be expected to overcome unlimited variation in the customer’s parts unless that variation was identified, tested, and included in the original process requirements.
Advanced seam tracking, vision, focus control, beam oscillation, and adaptive processing may increase the usable window. They do not make part geometry, material condition, and fit-up irrelevant.
This is an important part of process ownership even before final acceptance.
The integrator owns demonstrating the machine against the agreed requirements. The customer owns providing suitable parts and accurate process requirements when those items are included in the customer’s scope.
Why the customer must own the process window
After acceptance, the equipment supplier and integrator normally cannot control:
- Incoming material lots
- Surface preparation and cleanliness
- Product dimensional variation
- Joint fit-up
- Fixture adjustment and wear
- Operator practices
- Preventive maintenance
- Protective-window replacement
- Gas quality and flow
- Recipe access and modification
- Production duty cycle
- Inspection frequency
- Changes to upstream or downstream operations
Any one of these conditions can move a process closer to the edge of its demonstrated window.
Several small changes can also combine to create a defect, even when no individual change appears significant.
The integrator may be able to help identify the problem, but it cannot continuously own conditions inside a customer’s factory that it does not supervise or control.
This is why the continuing process owner must be located within the customer’s organization.
The laser can be healthy while the process is not
When a weld, cut, clad layer, or cleaned surface begins to change, the first reaction is often:
“Something must be wrong with the laser.”
Sometimes that is correct.
Frequently, however, the laser source is only one part of the process chain.
TRUMPF notes that laser power at the workpiece may change following replacement of a fiber-optic cable or focusing optic, or because of contamination on the protective glass. Its CalibrationLine system checks focal position and laser power at the workpiece rather than relying only on the commanded output of the laser source.[6]
That distinction matters.
A laser source can report its expected output while contamination, optical alignment, focal shift, beam delivery, or processing-head condition changes what actually reaches the part.
The same principle applies outside the optical system.
Precitec identifies focus position, seam position, joint gap, weld geometry, and penetration depth as conditions that can affect laser-welding quality and may need to be monitored during production.[7]
IPG Photonics similarly identifies poor fit-up, variation in incoming parts, and contamination of the workpiece or optics as possible causes of weld defects—even when the laser system itself continues to produce a stable optical output.[8]
This is why troubleshooting only the commanded laser parameters can miss the real problem.
Another made-up shop-floor story
Here is one more made-up example. It combines several conditions that are commonly encountered around automated laser systems, but it is not a factual account of one company.
A laser-welding cell passes acceptance and runs well during its first few weeks. Later, occasional shallow welds begin appearing.
Maintenance checks the laser and finds no source alarm. Production confirms that the correct recipe is loaded. Quality inspects several finished parts, but the problem is intermittent.
Eventually, the team identifies three small changes:
- A new material lot has a slightly different surface condition.
- A fixture locator has begun to wear, changing the joint position.
- The protective window has accumulated light contamination.
None of these changes appears large enough to explain the problem by itself.
Together, however, they move the process across the edge of its usable window.
The laser source may still be operating within specification. The integrator may have delivered exactly what was required. The machine may still be mechanically functional.
The problem exists because the complete production process has changed.
The lesson is not that someone made a terrible mistake. The lesson is that each department was examining only one part of a process that needed an identified internal owner.
A practical division of responsibility
There is no universal responsibility chart that applies to every contract, machine, or application.
The exact obligations should be defined in the purchase agreement, functional specification, acceptance documents, warranty terms, and service agreement.
However, this is the practical division I would recommend.
Product engineering and quality define what is acceptable
Someone must define the required result before a process can be developed and accepted.
That definition might include:
- Weld penetration and fusion
- Joint strength
- Allowable porosity, cracking, undercut, or spatter
- Cut geometry and edge quality
- Clad height, dilution, and bonding
- Surface-cleanliness requirements
- Dimensional and cosmetic requirements
- Inspection frequency and measurement method
ISO 13919-1 defines quality levels for imperfections in electron- and laser-beam-welded joints involving steel, nickel, titanium, and their alloys.
The standard also makes an important distinction: its quality levels concern production quality and do not, by themselves, determine whether a finished product is fit for its intended purpose. That decision remains with the responsible designer, manufacturer, user, and other involved parties.[9]
The process team should not be asked to “make a good weld” without a measurable definition of what a good weld is.
The laser manufacturer owns the performance of its equipment
The laser manufacturer should define and support the performance of the laser source and any beam-delivery equipment included in its scope.
This may include:
- Output specifications
- Beam characteristics
- Interfaces and alarm behavior
- Cooling and environmental requirements
- Recommended maintenance
- Calibration or verification methods
- Service limits
- Replacement-component specifications
- Warranty support
The laser manufacturer should help determine whether its equipment is operating correctly.
It cannot, however, control incoming material, fixture wear, part fit-up, motion-system calibration, production practices, or recipe changes made inside the customer’s facility.
The integrator owns the agreed complete-cell performance through acceptance
The integrator brings together the laser, motion system, fixtures, controls, safety system, gas delivery, wire or powder system, monitoring equipment, and software.
During development and acceptance, the integrator should demonstrate that the complete cell—not merely the laser source—meets the agreed requirements.
That demonstration must be based on the agreed parts, materials, tolerances, utilities, inspection methods, and operating conditions.
A good handoff should ideally include:
- Qualified recipes and permitted adjustment ranges
- Test-part and material information
- Acceptance results
- Measurement and inspection methods
- Power and focus verification procedures
- Fixture setup and inspection requirements
- Preventive-maintenance instructions
- Alarm and troubleshooting guidance
- Process-monitoring baselines
- Backup and restore procedures
- Training for operators, technicians, and engineers
- A list of changes that require review or requalification
Once the system meets the acceptance criteria and is formally accepted, the integrator’s continuing responsibilities are generally governed by the contract, warranty, service agreement, and any additional support purchased by the customer.
NASA’s specification for control and qualification of laser powder-bed fusion processes offers an example of this broader approach. It connects process definition and qualification with equipment maintenance, calibration, facility qualification, and personnel training.[10]
Although that document applies specifically to laser powder-bed fusion, the same general thinking can be useful across many laser manufacturing processes.
The customer owns continued production control
After handoff, one person or group inside the customer’s organization should be identified as the process owner.
That person does not need to personally perform every maintenance, engineering, production, or quality task.
The process owner needs the authority and information required to coordinate them.
The owner should understand:
- Which variables are controlled
- Which variables are only observed
- What the warning and stop limits are
- Who may edit a production recipe
- What maintenance work requires verification afterward
- When engineering or quality must become involved
- What process data must be retained
- What conditions require partial or full requalification
- Who can approve a return to production
- When supplier or integrator assistance should be requested
This is not primarily about deciding who receives blame.
It is about identifying who has the authority to stop, investigate, correct, and release the process.
Supplier support still matters
Customer ownership does not mean the supplier or integrator should respond with:
“The machine was accepted. It is your problem now.”
That may satisfy a narrow interpretation of a contract, but it is not a good way to build a long-term customer relationship.
A responsible laser manufacturer or system integrator should still want to help the customer succeed by providing:
- Technical support
- Troubleshooting assistance
- Replacement-component guidance
- Training
- Maintenance recommendations
- Process-development services
- Calibration services
- Remote or on-site diagnostics
- Upgrades and monitoring improvements
The difference is that support should not be confused with ownership.
A supplier can assist with a process it does not operate. An integrator can help diagnose variables it does not control. A laser manufacturer can verify its equipment without accepting responsibility for every production condition surrounding it.
Clear expectations are better for everyone.
The nominal recipe is not the complete process window
One common mistake is treating the saved production recipe as though it represents the complete qualified process.
It does not.
A useful process-control package should distinguish among four things.
1. The nominal recipe
These are the normal target settings used during production.
2. The demonstrated process window
These are the conditions and ranges that have actually been tested and shown to produce acceptable results.
3. The production control limits
These should generally be narrower than the demonstrated failure boundaries. They provide room to respond before the process begins producing unacceptable parts.
4. The finished-part acceptance criteria
These determine whether the output is acceptable. They should not be replaced by checking only that the machine used the commanded recipe.
The NIST/SEMATECH e-Handbook of Statistical Methods describes process monitoring as using measured data and control limits to identify conditions that may require investigation or corrective action.[11]
NIST has also published guidance on maintaining the traceability and trustworthiness of manufacturing data, including data from CNC and additive-manufacturing processes.[12]
Process data is useful only when we understand what it represents, where it came from, and whether the measurement system itself can be trusted.
Process monitoring does not eliminate ownership
Modern laser systems may monitor:
- Optical emissions
- Back reflection
- Temperature
- Acoustic signals
- Keyhole or penetration depth
- Weld geometry
- Seam position
- Finished surface shape
These tools can be extremely valuable.
However, someone still needs to establish:
- What a normal signal looks like
- Which physical defect or process change the signal represents
- How warning and reject limits were determined
- Whether those limits remain valid after a material or process change
- How the system is checked after service or sensor replacement
- What action an operator should take after an alarm
Monitoring should support the process window rather than substitute for understanding it.
A green screen does not automatically prove that every required part characteristic is acceptable. It proves only what the monitoring system has been configured, correlated, and validated to evaluate.
Changes that should trigger a process review
Not every change requires complete process requalification, but the decision should be deliberate and documented.
Typical review triggers may include:
- A new material supplier, alloy, coating, or thickness
- A change in joint design or part tolerance
- Major fixture repair or replacement
- Robot, CNC, or scanner recalibration
- Replacement of the processing head, delivery fiber, or focusing optics
- A change in protective-window type
- Laser, controller, or monitoring-software updates
- A revised beam shape, focal position, or oscillation pattern
- A change in shielding-gas delivery
- Replacement of a process-monitoring sensor
- A sustained shift in process data
- Repeated unexplained nonconformances
- Moving a qualified recipe to another machine
The important question is not simply:
“Did we change the laser power?”
The better question is:
“Could this change affect the conditions under which the process was originally demonstrated and accepted?”
So, who owns the laser process window?
My answer would be:
The equipment manufacturer owns the performance of its equipment within the agreed specification and warranty.
The system integrator owns the agreed performance of the complete system through development, testing, and acceptance—provided the customer supplies the agreed parts, materials, process requirements, and operating conditions.
After the machine and process have been accepted, the customer owns the continuing production process window.
The supplier and integrator should remain available as knowledgeable partners, but they cannot own production variables that are outside their control.
Customer ownership should not sit vaguely between production, engineering, quality, and maintenance. It should have a name attached to it.
A good handoff therefore does more than prove that the machine can make an acceptable part. It transfers enough knowledge, documentation, measurement capability, and training for the customer to maintain the process after the supplier’s application engineer has left the facility.
When a laser process begins drifting at two o’clock in the morning, the most useful questions may not be:
“Whose machine is this?” “Can we make a warranty claim?” “Can we call the integrator?”
The more useful questions are:
Who owns the process window inside our organization? Who owns the evidence that we are still operating within it? Who can authorize a process change? Who can approve the return to production?
How is this handled in your facility?
Is the process window formally documented and controlled, or does much of it still live in an application engineer’s notebook?
References
[1] International Organization for Standardization. ISO 15609-4:2009 — Specification and qualification of welding procedures for metallic materials: Welding procedure specification, Part 4: Laser beam welding.
[2] International Organization for Standardization. ISO 15614-11:2025 — Specification and qualification of welding procedures for metallic materials: Welding procedure test, Part 11: Electron and laser beam welding.
[3] American Welding Society. AWS C7.4/C7.4M:2017-AMD1 — Process Specification and Operator Qualification for Laser Beam Welding.
[4] International Organization for Standardization. ISO 17662:2025 — Welding: Calibration, verification and validation of equipment used for welding, including ancillary activities.
[5] U.S. Food and Drug Administration. Process Validation: General Principles and Practices. This guidance applies to pharmaceutical manufacturing, but its distinction between process qualification and continued process verification provides a useful general manufacturing comparison.
[6] TRUMPF. CalibrationLine — Calibration of laser power and focal position at the workpiece.
[7] Precitec. Process Monitoring Technologies for Laser Welding.
[8] IPG Photonics. Laser Weld Monitoring: Techniques and How They Work.
[9] International Organization for Standardization. ISO 13919-1:2019 — Electron and laser-beam welded joints: Requirements and recommendations on quality levels for imperfections, Part 1.
[10] NASA Marshall Space Flight Center. MSFC-SPEC-3717 — Specification for Control and Qualification of Laser Powder Bed Fusion Metallurgical Processes.
[11] National Institute of Standards and Technology. NIST/SEMATECH e-Handbook of Statistical Methods — Process or Product Monitoring and Control.
[12] National Institute of Standards and Technology. Recommendations on Ensuring Traceability and Trustworthiness of Manufacturing-Related Data, NIST AMS 300-10.