How to troubleshoot particle fluctuations after product batch change?

Particle fluctuation occurs after product batch change, which is a common situation at the production site. For the same equipment and the same system, the particle data changes after changing batches. This fluctuation does not necessarily come from equipment failure, but is more likely related to changes in material packaging, cleaning status, fixture size, process actions, or material path.

During the investigation, specific changes before and after the batch change should be recorded and compared item by item, rather than directly suspecting filter failure. The following will start from the aspects of change recording, packaging and cleaning, fixture shielding, material path, and process actions.

Record specific changes in batch changes

Before troubleshooting, first record the content that has changed before and after the batch change:

• Material supplier or batch;

• Packaging form and unpacking method;

• Material cleaning status and processing procedures;

• Size and shape of fixtures and jigs;

• Equipment programs and action parameters;

• People and operations.

Listing these changes will help narrow down the scope of investigation. If multiple variables change at the same time, they can be checked individually under permitted conditions to avoid simply establishing erroneous cause and effect.

Packaging and cleaning status are common sources

New batches may be packaged differently than previous batches. Packaging materials, closures, liners and labels can all produce particles. Changes in unpacking methods can also affect particle release.

During inspection you should pay attention to:

• Whether the packaging material is easy to chip;

• Whether the unpacking method produces dust;

• Whether the surface of the material is clean;

• Whether additional cleaning steps are required.

For particles brought in by materials, please refer to How to distinguish external and internal contamination when particles exceed the standard? , understand the method of source differentiation.

Changes in fixture and workpiece dimensions may block air supply

The new batch may have different workpiece dimensions, fixture height, or fixture shape than the previous batch. These changes may alter local airflow paths:

• Taller fixtures create a shadow under the air supply surface;

• Larger workpieces change the direction of airflow;

• The location of the new fixture blocks key operating areas;

• The way the workpiece is placed is changed so that the product is in different air flow areas.

When judging, the new batch of workpieces and fixtures should be placed in the actual location and observe whether the airflow can still cover the sensitive area. For the impact of stacking items on the workbench, please refer to Will stacking items on the workbench create a pollution dead zone? , to understand the impact of occlusion on airflow.

Changes in material routing and handling methods

After changing batches, the entry and exit paths and handling methods of materials may change. New turnover containers, new handling tools, or different temporary storage locations may introduce particles or change local airflow.

During inspection, you should confirm:

• Whether the turnover container is clean;

• Whether the handling tools produce particles;

• Whether the temporary storage location is in a protected area;

• Whether the material path passes through the source of pollution.

For material path planning, please refer to What are the prerequisites for purifying only key workstations? , understand the requirements for forward and backward transfer protection.

Changes in process actions and program parameters

New batches may correspond to different process procedures. Changes in action speed, frequency, residence time and movement trajectory will affect local airflow and dust production.

When checking, compare:

• Equipment action speed and frequency;

• Robot movement trajectory;

• Processing time and dwell position;

• Whether the process parameters change.

If the particle fluctuations are synchronized with an action, focus on checking that action. For the impact after the startup of process equipment, please refer to What should I do if the cleanliness of the process equipment drops after it is started? , understand the staged observation method.

Compare equipment operating settings and environmental conditions

The fluctuation of particles after batch change is not necessarily related to the material. Equipment operating settings, filter status, and environmental conditions may also change.

Should check:

• Whether the fan speed and operating settings change;

• Is the filter pressure difference normal?

• Whether the room pressure difference and temperature and humidity are stable;

• Whether the operating status of air conditioning and exhaust has changed.

Changes in these conditions may also cause particle fluctuations. For the impact of turning on the air conditioner, please refer to What should be checked if particles increase after the air conditioner is turned on? , understand the investigation direction of changes in environmental conditions.

Check items individually to avoid changing multiple variables at the same time

Multiple variables may change at the same time after changing batches. Suggestions during investigation:

• First restore the original batch conditions and confirm whether the particles have been restored;

• Then change packaging, fixtures, procedures and other variables one by one;

• Only change one condition at a time and record the particle changes;

• Record the conditions and results of each comparison.

Item-by-item verification helps establish cause-and-effect relationships. If multiple conditions are adjusted at the same time, it can be difficult to determine which factor is the main cause.

Record and establish batch change requirements

After the inspection, the results should be recorded and inspection requirements should be formed when changing batches:

• New batch packaging and cleaning requirements;

• Fixture and workpiece placement requirements;

• Material routing and staging requirements;

• Program parameter confirmation requirements;

• Verification requirements after batch change.

Incorporating batch change requirements into production management can reduce particle fluctuations between subsequent batches. If the batch change involves a new material path, please refer to What are the expansion conditions for using independent modules in clean systems? , plan the protection scope in advance.

Equipment selection and terminal matching

The troubleshooting involves equipment and filtering configuration, please refer to FFU clean air supply products and EFU equipment side fan filter unit . Filter installation, sealing and leak detection requirements can be learned HEPA and ULPA filters . If you are still unclear about the difference between space rating and filter efficiency, you can read What is the difference between cleanliness level and filtration efficiency?。

Project judgment example

After the batch change of a certain project, the particles at the work station were high. The investigation revealed that the new batch of fixtures was taller, creating an airflow shadow under the air supply surface. Adjustment method: Adjust the clamp position and air supply direction to keep the product within the effective protection range. Particles restored after adjustment.

The particles of another project fluctuated after the batch was changed, but the fixture and procedure remained unchanged. The investigation found that the new batch of packaging materials were prone to chipping. Adjustment method: Adjust the unpacking method and cleaning process, and add material cleaning steps. After adjustment, particle fluctuations are reduced.

These two situations indicate that the particles fluctuate after the product batch is changed. It needs to be investigated from multiple directions including materials, fixtures, paths and procedures. The failure of the filter cannot be suspected.

Key points for selection and acceptance inspection

Aili industrial equipment supporting support

Particle fluctuations after product batch changes may come from changes in materials, fixtures, procedures or environmental conditions. Aili Industrial has collaborative capabilities in fans, motors, filters, control systems and complete machine assembly links. It can cooperate to check air supply coverage, filter status, operating settings and air flow paths during batch change inspections, helping to determine whether the source of fluctuations is material introduction, fixture obstruction or changes in system conditions, instead of just judging the filter status based on particle readings. Specific models can be viewed FFU clean air supply products , the supporting equipment can be viewed EFU equipment end fan filter unit , please refer to the filter package. HEPA and ULPA filters。