How pierce count affects part manufacturing time more than metres of cutting ART-132

What piercing means and why it is not “zero” time

In laser cutting, piercing is the start of material penetration before further contour cutting. It is a separate process phase that depends on material, thickness, surface condition, equipment configuration, gas, set technology, and part geometry. There is no single correct piercing time for every sheet and machine, so it is unsafe to transfer a random number from another example into your own calculation.

For production, not the word “piercing” but its repeatability matters. If a part has tens, hundreds, or thousands of internal contours, every start adds a fraction of the cycle and together they can become the main share of time. Movements between contours, position control, measures to preserve small elements, and possible pauses built into the technology are added as well.

The practical conclusion follows: two parts with similar area and identical cutting length can have different machine time. One will be a large contour with several holes, the other a perforated panel, grid, or part with many elements. They need different estimation and can affect the production queue differently.

What the cycle consists of

| Component | What happens | Why it cannot be ignored | |---|---|---| | Job preparation | Program selection, file check, sheet placement | Affects small batches and frequent changes | | Positioning and movement | Transition to the next contour | Grows with complexity and spread of elements | | Piercing | Start of material penetration | Repeats for internal contours and separate parts | | Contour cutting | Motion along the cut line | Depends on length, geometry, and technology | | Controlled transitions | Avoiding risk zones, small elements, sequence | May be needed for stability and quality | | Unloading and sorting | Separation, marking, downstream transfer | Often part of the real route, though not cutting time |

This table does not provide a universal formula, but it shows why a program calculation or observation of the real cycle is more accurate than estimating “metres multiplied by speed.” Results can also differ between batches because of material, wear of consumable components, gas stability, and program preparation.

When pierce count becomes critical

This is most often seen in perforated panels, ventilation grilles, parts with numerous mounting holes, narrow slots, meshes, and elements with many internal windows. But a large number of contours does not automatically mean a part is “bad.” It can be functionally necessary. The technologist's task is to understand whether every geometric feature is needed, whether it can be changed without loss of function, and how to arrange the process safely.

Do not give the designer the simple instruction “fewer holes.” It is more correct to show the connection to the production scenario: which holes are critical, which are functionally linked, what the next operation requires, whether ventilation form can change, and whether another fastening method is allowed. For some products, another technology or a combined route may be an alternative, but that decision needs separate assessment, not a general rule.

How to verify the impact on a real part

The first step is not merely timing the finished product with a stopwatch, but looking at the program. Count internal contours, separate parts in the nest, operation sequence, and estimated CAM time. Then select two or three parts with similar cutting metres but different contour count and compare them under the same conditions.

During this comparison, record material and thickness, program version, number of sheets, machine time, pierce count from CAM or the technological report, need for manual intervention, quality of critical zones, and condition after unloading. If a part is to be revised, first record the baseline variant. Otherwise it is impossible to know whether a change truly improved the process or simply changed launch conditions.

What can be optimised and what cannot be promised

CAM systems help build nests, cutting order, and technological rules. Official materials from software makers describe automation of these tasks, yet the automatic result still needs specialist checking, especially for complex parts. Manual adjustment can be justified when order priorities, stability of small elements, deformation direction, or unloading specifics must be considered.

Optimisation must not mean carelessly reducing pierces or changing paths for a nice number in a report. Such changes can affect edge quality, thermal influence, sheet stability, part separation, and process safety. Without specific materials and programs, one cannot promise that every part will become faster by a certain percentage.

Part-analysis algorithm

1. Take the current file and record its revision, material, thickness, and batch volume. 2. Separate the outer contour, internal holes, slots, perforation, and separate elements. 3. Check the estimated time, number of starts, and operation sequence in CAM. 4. Compare with a part of similar cutting length but a different contour structure. 5. Assess not only machine time but also required sorting, finishing, and the next operation. 6. If necessary, discuss with the designer only changes that do not destroy product function. 7. Verify the changed version in a separate test and retain a record in the documentation.

Typical mistakes

Dividing price or time only by metres of cutting. This metric is useful for rough orientation, but it cannot see contour structure, start-up, and manual labour.

Counting holes without geometry. Two holes may require different scenarios depending on size, position, material, and subsequent function. No conclusion can be made from quantity alone.

Changing the drawing without agreeing the function. Manufacturing convenience does not justify loss of ventilation, strength, compatibility, or customer requirements.

Treating a CAM forecast as a guarantee. The forecast depends on settings, technology libraries, and actual conditions; it must be checked in a real launch.

Working scenario: why two “identical” panels have different cycles

Imagine two parts with the same format and similar cutting length. The first is a solid panel with several mounting holes. The second is a ventilation panel with dozens of small windows and internal slots. If only the contour line is counted, they look nearly equal. But the second has more starts, short transitions, and zones where technology must preserve small elements or define cut order.

Two tasks should be separated in the calculation. The first is commercial: understand why the panel needs different time and perhaps a different cost from the solid one. The second is technological: verify whether all geometry is needed and whether it can change without harming function. A technological decision must not automatically be transferred into the drawing: ventilation can have regulatory, acoustic, thermal, or design requirements. But analysis itself helps avoid an “eyeball” dispute.

It is useful to prepare a one-page short report: a part sketch, contour-group count, CAM machine time, actual test time, visible manual operations, and questions for the designer. It does not oblige anyone to redesign the product, but makes the source of cost visible. Repeating products particularly benefit: one check can improve many following batches.

How to speak with the designer without conflict

The worst wording is “this part cuts badly.” It does not explain what must change and may look like an attempt to simplify shop work at the expense of the product. Better is: “This area contains many separate contours; they form a significant part of the cycle. Is there a functional reason for this pitch, shape, and count?” Then discuss not technology as an end in itself but function: airflow, fastening, mass, access to the assembly, appearance, and standards.

Sometimes nothing needs to change. Then the analysis becomes the basis of honest planning: the part enters the production queue with its real cycle, rather than being compared to simpler parts by cutting metres. If the function allows alternatives, the change must go through the normal drawing-revision process and be checked on a sample.

Data that should remain after analysis

Keep the DXF version or other source file, material and thickness data, CAM-program version, launch conditions, quality conclusion, and a short explanation of possible changes. This helps with repeat orders, handover to another operator, or price discussion with the customer. It should not turn into a complex report for every small batch: detailed analysis is mainly needed for serial, expensive, problematic, or critical items.

When piercing is not the problem

A large number of starts is only one possible cause of a long cycle. Similar effects can be created by low useful nesting yield, frequent operator waiting, material instability, an incorrect order queue, difficult unloading, or manual cleaning after cutting. The correct sequence is therefore: first divide time into components, then see the largest contribution, and only then change the program or design.

If piercing proves to occupy a small share of the cycle, that too is useful. It prevents spending time optimising a secondary factor when the real bottleneck is after the machine. Such analysis helps planning: parts with many contours can be queued with a realistic estimate, rather than trying to offset delay by randomly accelerating modes.

What cannot be determined without data

Without the file, material, thickness, machine, technology settings, nesting plan, and quality requirements, it is impossible honestly to name machine time, price, pierce count, required cut sequence, or savings after a design change. General recommendations must also not be turned into equipment operating modes.

Checklist for evaluating a complex part

• [ ] File revision, material, thickness, and batch volume are known.
• [ ] Internal contours, slots, and perforation are separated from the outer contour.
• [ ] CAM estimate is compared with a real launch, not accepted on trust.
• [ ] Cutting time is not mixed with preparation, sorting, and finishing.
• [ ] Potential design changes are reviewed together with functional requirements.
• [ ] Test results are recorded so that they can be repeated.

Pierce count is not a reason to simplify every part. It is a signal to examine the entire process: what forms the time, where manual work arises, whether every geometric feature is truly needed, and which option gives the best balance between product function and production cycle.

How to use the result in planning

When real time has accumulated for a group of parts, use it not as a fixed standard but as a planning basis. Parts with many contours should be placed in a separate category so they do not receive the same benchmark as simple contours of similar size. This makes delivery promises easier and reduces urgent queue reshuffling.

At the same time, data need periodic checking. Materials, lots, program versions, consumable components, operator skills, and sorting rules change. If time differs materially from the previous value, first find the cause rather than demand that the operator “return the old speed.” Sometimes an increase results from necessary quality control or a changed part function, not from process deterioration.

Planning becomes more accurate when it sees work structure. Cutting metres can remain one metric, but must not be the only one. Combining data on contours, material type, nesting, repeatability, and downstream processing gives a much more honest picture for production and for a customer who expects a clear lead time and cost explanation.

Separate the part report into three time levels

To keep pierce count from becoming a convenient but false explanation for every delay, an internal report must separate three levels. The first is the machine cycle: positioning, piercing, cutting, and technological transitions visible in the program and actual launch. The second is preparation time: revision check, sheet placement, job selection, and approval of changes. The third is post-cut time: unloading, sorting, marking, inspection, and handoff to bending, welding, or assembly.

This division is not for formal accounting. For example, a perforated panel can indeed have a longer machine cycle because of many starts. But if the main delay arises after cutting from manually sorting hundreds of small elements, changing the path will not solve the commercial problem. Conversely, a simple part may cut quickly but wait long to start because its file revision is unchecked. When these causes are mixed into one number, the team argues about machine speed instead of improving the actual route.

| Level | What to record | What decision it supports | |---|---|---| | Machine cycle | Program version, contour count, launch fact, variance | Comparing geometry and CAM approaches | | Preparation | File, material, job, and change status | Removing delays before launch | | Post-cut | Sorting, inspection, manual finishing, next operation | Assessing the full route and customer lead time |

For a serial or costly item, it is appropriate to leave a short conclusion: “time increases mainly because of piercing,” “sorting is the constraint,” or “file clarification is needed.” This is not a universal standard and does not replace a process sheet. It does mean the next calculation starts from a verified fact, not an assumption that identical contour length means identical cost.

Boundary between estimation and a technological decision

For a preliminary estimate, the file and a few input data can be enough. But when a part is critical, serial, or has many small elements, the technological decision must be confirmed by a test. This is especially important when the estimate affects delivery time, customer cost, or the next operation. The approach does not slow production: it directs additional attention where an error will later cost more.