Aluminum Laser Head Window Cartridge Air Purge CNC Milled 0.01mm Sealing Fit

The Seal Decides Whether The Cartridge Works

A protective window cartridge carries the optical glass, seals the head against dust and coolant mist, and in purged heads also feeds clean air across the window face. Everything that determines whether it works is machined geometry: an O-ring groove of the right width and depth so the ring is compressed and not pinched, a sealing face flat enough that the ring sees uniform load, a window bore concentric with the groove, and a purge port that actually breaks through where the drawing says it does.

We machine these cartridges from solid aluminium plate or billet, cutting the bore, groove and sealing face in one set-up so they cannot drift relative to each other, then drill and tap the purge port in the same programme. Anodizing follows with the grooves and threads masked, because an extra 10 µm inside a groove changes the squeeze ratio and a coated thread stops accepting the fitting.

How The Cartridge Is Built

Precision Table

Groove geometry is quoted against your O-ring call-out rather than against a table we invented: tell us the cord diameter and the squeeze you want, and we machine the width and depth to produce it. Where the drawing leaves the groove nominal, we recommend a size and send the number for your approval before cutting.

Materials, Finishes And Custom Variants

• Material: 6061-T6 standard; 7075-T6 for thin sections; 304 or 316L stainless for coolant-heavy or wash-down environments; brass for non-magnetic fixtures.
• Finish: Type II black, clear or silver anodize 10-15 µm; hard anodize 25-50 µm; chromate conversion for RF or conductive requirements; laser marking after coating.
• Sealing options: face O-ring groove, radial groove, double groove for two windows, flat gasket land, labyrinth dust step.
• Air path: single purge port, dual port, internal gallery, nozzle break-through, sintered restrictor pocket.
• Optics: round, square or rectangular window seat, chamfered lead-in, retaining step, clip groove.
• Size: 20 mm to 200 mm body, thickness 4 mm to 25 mm, threads M3 to M8.
• Documentation: first article report, material certificate, anodize batch record, leak test record where requested.

Confidentiality For Optical And Head Designs

Cartridge drawings expose window size, purge routing and the internal geometry of a laser head, which is why we treat the file as confidential from the first contact. A mutual NDA is signed before any drawing or model is opened — ours in English or Chinese, or your own form — and a countersigned copy goes back to you before work starts. Only the project engineer, the milling programmer and the cell supervisor can access the file, which lives in a restricted folder rather than on the shop network. No photographs of customer parts are taken for our catalogue or website, customer parts are never displayed or reused as samples, subcontracting needs your written approval, and at program close files and inspection data are deleted or returned with written confirmation.

Who Machines It

Dongguan Changxinda Precision Technology Co., Ltd has been machining custom parts since 2008: 15+ years, 90 to 100 staff, 50–60% exported to North America and Europe, 200+ customers served, turnover in the RMB 10–20 million band. The plant runs 4-axis and 5-axis CNC machining centres, turn-mill combined lathes and CNC lathes, with an ISO 9001:2015 quality system covering medical, robotics, automotive, aerospace, automation, laser, LED, lithium battery and precision instrument programs. Milling, turning, anodize coordination and inspection are all in our own hands in Dongguan, which is why we can commit to a date rather than a range.

Ten Sectors, One Workshop

These are the ten industries our parts ship into. Each line is a category we machine regularly, with the parts customers actually order.

All ten sectors run through the same plant and the same ISO 9001:2015 inspection discipline — only the material, finish and documentation package change.

Delivery And Repeatability

• Prototype: 3–7 working days after drawing approval including anodize; 10–14 days with leak test and hard anodize.
• Small batch 10–100 pcs: 7–14 working days in a reserved milling cell slot.
• Repeat orders: run from archived programs, fixtures and anodize racks; the groove depth and bore are cut to the same mid-band values every time.
• Capacity: 10,000 pieces per month across the plant.
• Visibility: a dated progress note with photos of your actual cartridges at milling, anodize and leak test.
• Shipping: sealing faces filmed, parts bagged, foam-lined export carton, express or air and sea per your forwarder.
• Rush: overtime slots and an express anodize line held weekly; tell us the deadline and we confirm before you place the order.

Buyer Questions

Q: How do you set the O-ring groove for our seal?
A: From your cord diameter and the squeeze you want, normally 15–25% for a static face seal. We calculate width and depth, include both numbers on the drawing for your approval, then hold groove width and depth to ±0.02 mm and check the profile with a gauge on the first part of every batch.

Q: Does anodizing change the seal or the thread fit?
A: It would if we coated everything. Grooves, sealing lands and threads are masked, so the squeeze ratio and the 6H thread are unaffected; the visible body still gets the full 10–15 µm Type II coating. Where a conductive surface is needed for RF or grounding, we use chromate instead of anodize on the masked areas.

Q: Can you machine the purge port so the air actually reaches the window face?
A: Yes, and it is checked. The port is drilled to breakthrough in the same programme as the bore, deburred inside, and verified with a pin and a low-pressure air check. Where the design calls for an internal gallery or a restrictor pocket, we mill it before anodizing so no coating blocks the path.

Q: What flatness can you hold on the sealing face, and why does it matter?
A: 0.02 mm across the seal land. Beyond that the O-ring sees uneven compression, the leak rate becomes unpredictable, and dust finds the low side. We machine the face in the same set-up as the groove and check it on a granite plate before anodize and again after.

Q: Minimum order and quotation speed?
A: One piece, no tooling charge. Send the drawing or model with the quantity and required date; a written quotation normally returns within 24 hours, including a groove and material recommendation where the drawing leaves them open.

Q: Will you sign an NDA and keep the part out of your marketing?
A: Yes. NDA signed and countersigned before the file is opened, access limited to the engineer, programmer and supervisor, no photographs of customer parts, and nothing about your program in our catalogue or website without written permission.

Send The Drawing, Get A Date And A Price

Attach the drawing or model with the quantity and the deadline, and you will get a quotation, the process route including anodize and leak test, and a firm delivery date. NDA paperwork can be dealt with in the same exchange.