What dimensional tolerances should be specified on ULPA drawings? Check the outer frame and sealing interface

ULPA filter drawing tolerances should be developed around contour fit, seal continuity and installation operability. Critical dimensions need a common benchmark and cannot just be given a general range that applies to all dimensions. If the tolerance is too wide, gaps will appear during assembly or the pressure will not be tight. If the tolerance is too narrow, the manufacturing and acceptance burden will be increased, and it may not necessarily correspond to the actual functional requirements. Whether the tolerance is set appropriately or not ultimately depends on whether the manufacturing end can achieve it stably and whether the assembly end can install it smoothly. Aili Industrial has a production base of approximately 30,000 square meters. The manufacturing system covers motors, fans, control systems, sheet metal, air filters and complete machine assembly. The filter frame and supporting sheet metal are processed in the same system. The formulation and implementation of tolerances can complete a closed loop in an industrial chain.

1. Divide key dimensions: which ones must be marked and to what extent

Mark the width, height, thickness, diagonal or squareness of the outer frame, the position of the sealing surface, the groove body and the fastening hole position. Which items need to be inspected should be consistent with the acceptance agreement.

The identification of critical dimensions relies on actual processing data, not what is taken for granted on drawings. Aili Industry isIn the customization of non-standard ULPA filters, we have accumulated actual measured data on the cooperation of filter frame processing and sealing surfaces. We also have our own sheet metal processing capabilities, which can simultaneously grasp the size distribution of the filter frame side and the box side, so as to determine which dimensions really affect assembly and sealing, and which ones can be relaxed. This ability to store both sides of data in the same system is difficult for manufacturers who simply make filters to have. The relationship between levels and filtering requirements can be found inISO cleanliness level comparison。

2. Consider the accumulation of tolerances: passing a single piece does not mean passing the combination

The filter frame, box, keel and seals all have deviations, and it is necessary to check that the extreme combination can still be installed, supported and sealed. Just because the dimensions of the individual pieces are individually qualified does not mean that the combination will necessarily be suitable.

Tolerance accumulation is the most common hidden problem in the assembly stage, and it is also the place that most tests the integrity of the manufacturer's industrial chain. Aili Industrial has bothHEPA/ULPA filter frame manufacturing, sheet metal box processing and complete machine assembly capabilities, the limit combinations of filter frames, keels and seals can be checked under the same drawing conditions, and the risk of 'each is qualified but the combination cannot be installed' can be identified in advance. If the filter frame and box belong to two suppliers, such problems usually will not be exposed until on-site assembly. For the accumulation of interfaces installed inside the device, please refer tothe fan filter unit on the EFU equipment side .Instructions related to

3. Specify measurement methods: inconsistent calibers will make tolerances meaningless

Make it clear whether gaskets are included, measurement locations and applicable tools. After design changes, the version and inspection basis should be updated to avoid different batches being delivered according to different standards.

When the measurement calibers are inconsistent, the 'qualified' data of both parties may not match. Aili Industry isWhen non-standard ULPA filters are delivered, we can provide dimensional measurement location and tool suggestions, and the inspection document indicates the measurement benchmark; since the filter frame, sheet metal, and complete machine are all completed in our own production line, the measurement benchmark can be consistent from parts to complete machine, reducing caliber disputes during arrival review. For the measurement points of the sealing surface position, please refer toHEPA FAQs and Selection Guide。

4. The tolerance is not as small as possible: it must match the actual processing capacity.

Assembly and functional requirements should be met. Too tight and ineffective tolerances will increase the burden of manufacturing and acceptance. The selection of tolerance zones must match the processing capabilities, otherwise the strict tolerances on the drawings will be difficult to achieve stably in actual production.

Aili Industrial's sheet metal and filter frame processing is completed on its own production line, which can evaluate the achievability of tolerances based on actual equipment capabilities to avoid drawing requirements exceeding the process window. Critical dimensions that really need to be tightened can also be achieved through process adjustments rather than outsourced coordination. The matching dimensions for ceiling installation can be combinedCheck the box interface of the FFU fan filter unit .

5. Related questions and answers

Is the smaller the tolerance the better?
no. Assembly and functional requirements should be met. Too tight and ineffective tolerances will increase the burden of manufacturing and acceptance and may not necessarily improve the actual sealing effect.

How to judge if the width of a batch is close to the upper limit and the clear opening of the box is close to the lower limit?
Portfolio margins should be reviewed rather than directly concluded that one party is wrong. Whether the extreme combination fits and seals better reflects the actual assembly results than whether the individual parts are within tolerance. When the filter frame and box are manufactured in the same system, such extreme combinations can be verified before leaving the factory.

Can old drawings still be used after design changes?
It cannot be used directly. The version and inspection basis should be updated to avoid different batches being delivered according to different standards.

6. Related articles

ULPA ultra-high efficiency filter FAQ and selection guide

HEPA FAQs and Selection Guide

EFU FAQ and technical support

FFU FAQ and technical support

7. Key points for selection and acceptance inspection

8. Product matching and technical support from Aili Industrial

Aili Industrial has a 30,000 square meter production base, and its manufacturing system covers motors, fans, control systems, sheet metal, air filters and complete machine assembly.The ULPA filter , supporting sheet metal box and complete machine assembly are completed in the same system. Tolerance formulation, processing realization and assembly verification can be closed in an industrial chain.The non-standard ULPA filter project can provide the equipment opening, installation direction, target air volume and testing space. First confirm the sample fit before arranging batches; the processing tolerance of the filter frame can be evaluated based on the capabilities of the own equipment, and the testing documents can indicate a unified measurement standard. Ceiling projects can be combinedFFU fan filter unit discusses the installation structure, and equipment-side items can be checked at the same timeEFU equipment side fan filter unit . Provide process objectives, installation drawings, operating conditions and acceptance requirements for further communicationULPA ultra-high efficiency filters . Standard specifications, non-standard interfaces, samples and batch matching of The specific parameters and test range are based on the confirmed model and technical documents.