Automotive Lamp Housing Helium Leak Testing Machine Two Chambers 40s Cycle For Headlamp Sealing Inspection

A fogged headlamp is a warranty claim with a photograph attached, and the cause was decided months earlier at the bonding station. This two-chamber helium system proves the seal on every lamp housing at a production takt, at a charge pressure that will not distort a plastic part.

Why lamps are a different testing problem

People assume a lamp is just a box with a lens glued on. It is a box with a lens glued on that also has to breathe. That contradiction is where most test specifications fall apart.

A lamp needs a pressure-equalisation membrane — an ePTFE vent — or it will fog from the inside as it heats and cools. The membrane is designed to pass air and water vapour and to keep liquid water out. Put that lamp in a helium test and it leaks by design, straight through the vent. A supplier who has not thought about this will quote you a machine that rejects 100% of good lamps, and the argument then becomes about the machine rather than the process.

The second difference is the material. Polycarbonate and PP move with temperature, absorb a little moisture, and outgas under vacuum. A test recipe written for a metal part will read a plastic lamp as unstable and drift the result. The third is pressure: charge a lamp at 1 MPa and the lens bows, the adhesive sees a load it never sees on the vehicle, and you may damage a lamp that would have passed.

Our cycle is built around those three facts rather than retrofitted to them: low controlled charge pressure, chamber-side vacuum, a stabilisation window long enough for the plastic, and a vent-port strategy agreed with you before the fixture is cut.

Handling the breather: three options, one of which is yours

How a cycle runs

• Load and clamp — lamp into soft-faced fixture, pneumatic head seals the charge port, barcode scan for traceability.
• Evacuate — chamber pumps down. The lamp sees no internal vacuum, so the lens and housing are never loaded in a way the design does not allow.
• Stabilise — a deliberate pause while the plastic settles; the controller subtracts the background trend before it starts integrating.
• Charge and measure — helium at the recipe pressure, fixed integration window, result converted to a leak rate and compared with the limit.
• Recover and release — helium pulled back through the recovery loop, chamber vented, lamp released with a verdict and a stored record.

Technical parameters

What it finds

Setting the limit, and proving it before you commit

There is no universal conversion from IP67 or IP6K9K into a helium leak rate, because the answer depends on housing volume and on the pressure profile the standard applies. Anyone who offers you a table is guessing. What works is a short empirical exercise:

• Test ten production lamps and look at the spread. That tells you what "good" looks like on your line, on your moulding, in your climate.
• Test a lamp with a calibrated leak fitted to the vent seat or the bond line, and confirm the machine sees it.
• Set the reject line with margin — we usually work to about one third of the specified rate, so marginal lamps are caught before the vehicle assembly plant catches them for you.
• Repeat the study after a mould change. A new tool changes the wall thickness and the volume, and the limit should move with it.

In practice, our lighting customers end up between 1×10^-6 and 1×10^-7 mbar·L/s. The exact figure matters less than the discipline of writing down the method alongside it.

Compared with the alternatives

The comparison that matters is with air decay, because most lighting plants already own one. On a plastic lamp the air method fights the material: the housing absorbs heat, the internal volume is large, and the criterion is usually tighter than air can resolve inside a takt. Helium in a chamber sidesteps the fight instead of trying to win it.

Delivery, installation and the first month

• Fixture prove-out on your lamps before shipment, with video and the calibration certificate.
• Vent-port strategy and charge-port adapter agreed in writing before the fixture is cut.
• On-site commissioning: fixture adaptation for each lamp family, accept-limit correlation, operator training.
• Repeatability study on ten production lamps plus a calibrated-leak lamp, signed off with your quality engineer.
• 24-month warranty on mechanics, pneumatics and control; vacuum pumps per manufacturer terms.
• Changeover kit and recipe for a second lamp family, with fixture drawings handed over.
• Spares in Guangzhou: chamber seals, fixture faces, helium valves, pump service kits — 48-hour dispatch.
• Annual calibration with traceable certificate and remote support over the network.

Frequently asked questions

About Guangzhou Hejin Automation Control Technology

Since 2003 we have designed and built leak detection and electrical test equipment in Guangzhou, with 50–100 employees and about half of our production exported. The same engineering team commissions vacuum chamber systems for automotive air conditioning, battery and relay customers, so the recommendation for a lamp housing comes from production experience with sealed plastic assemblies rather than from a generic catalogue.

Each system is assembled, pump-down tested against a calibrated leak and recorded under its serial number before shipment. When you compare a result three years later, the original acceptance data is still on file.