Titanium hermetic laser welding requires both a sound weld and a verified package boundary. Shielding protects hot titanium, fit-up controls how the joint fuses, and inspection establishes whether the finished assembly meets its drawing and leak-test requirements. Improving only one of these areas can leave a different failure mechanism unresolved.
This guide addresses titanium housings and lids within a laser hermetic sealing process. It provides a development framework rather than a universal welding recipe. Material grade, wall thickness, joint geometry, internal components and the required service conditions must define the final process.
Confirm the material before setting parameters
Record the exact titanium grade, product form, condition and material certificate for both mating parts. Commercially pure titanium and titanium alloys should not be treated as interchangeable merely because both components look similar. Surface treatments and prior manufacturing operations also belong in the trial record.
For a first review, provide the lid and housing drawings, local wall thickness at the seam, tolerances, any coatings and the intended weld section. The titanium welding application page is a starting point for this discussion; the process must still be demonstrated on the actual material combination.
Protect more than the molten pool
Hot titanium can absorb atmospheric contaminants, so protection must cover the weld pool and relevant hot metal as it cools. TWI's titanium joining guidance describes the need to consider the face, root and trailing region. Its discussion also cautions that weld color alone cannot prove the absence of contamination.
On a closed housing, access to the root can be difficult. Review which surfaces become hot and whether the internal atmosphere protects them. A gas nozzle aimed at the visible bead may leave a different surface exposed. Corners, clamps and recessed features can change gas coverage around the same part.
Avoid using gas flow as the only control variable. Nozzle position, leakage in the delivery line, part orientation and the surrounding geometry also need repeatable settings. A process that works with an open fixture may change after guards or automation are added.
| Development question | Evidence to collect | Decision supported |
|---|---|---|
| Are the face and root protected? | Joint section, gas path and inspection of both surfaces where accessible | Local shielding arrangement or enclosed environment |
| Does protection continue through cooling? | Defined shielding duration and observations around the seam | Gas timing and part handling sequence |
| Does the process remain stable after loading? | Atmosphere records before and during a representative cycle | Purge, transfer and recovery criteria |
| Are corners behaving differently? | Location-specific images and sections | Motion, shielding or fixture changes |
Select an environment that can be verified
Local shielding can be evaluated where the joint is accessible and the sensitive surfaces can be protected consistently. An enclosed chamber or glovebox welding system may make sense when handling, internal atmosphere or complex coverage requires a controlled volume.
Write down how a loaded system reaches its release condition and how that condition is maintained during welding. Include material transfer and fixture loading in the trial cycle. An empty enclosure demonstration does not establish performance with production parts and fixtures inside it.
There is no single oxygen or moisture setting that qualifies every titanium package. Establish limits, sensor locations, response requirements and actions for an out-of-range condition through the project qualification plan.
Control cleaning and time to welding
Surface preparation should remove contamination without introducing a new source of residue. Define the approved cleaning method, tools, handling protection, drying and storage conditions. Keep the cleaned joint surfaces protected during inspection and assembly.
TWI identifies moisture-bearing surface layers as a contributor to hydrogen-related porosity in titanium welds. In a development investigation, track cleaning and storage history alongside laser settings. If two nominally identical batches weld differently, compare their surface preparation before assuming that the energy setting has drifted.
Do not transfer a chemical cleaning process from a general article directly into production. The product's materials, internal components and cleanliness requirements determine which process can be qualified.
Check fit-up in the clamped condition
Measure the joint as it will actually be welded. Free-state lid flatness does not show the gap after clamping, and a heavy clamp may close one area while distorting another. Record seam position, local gap, edge mismatch and the fixture's contact points.
For a thin lid, check whether the fixture changes the weld access or heat flow. For an autogenous weld, an excessive gap can leave insufficient metal to create the intended section. The acceptable gap is a qualified process variable, not a fixed value common to all titanium parts.
Sample the straight segments, corners and final overlap. If only one region is unstable, investigate the local fit-up and motion before applying a global parameter change.
Build the trial around the failure modes
Begin with representative parts and a documented nominal condition. Then vary relevant inputs within a controlled development matrix. Useful inputs can include fit-up, focus position, travel speed, pulse timing or power, and shielding conditions. Change a limited set of variables at a time so that the observations remain interpretable.
| Observation | First investigation | Evidence needed before release |
|---|---|---|
| Discoloration varies around the seam | Coverage, hot-surface exposure and local geometry | Shielding records plus qualified inspection criteria |
| Pores appear in sections | Surface history and process stability | Sections from representative locations and leak results |
| A corner has an irregular profile | Local gap, speed transition and heat accumulation | Corner sections and dimensional measurements |
| Package leaks despite a smooth bead | Closure transition and all other seal boundaries | Leak localization correlated with weld inspection |
| Package passes leakage but weld section is unacceptable | Non-through defects or insufficient fusion | Drawing-based weld acceptance, independent of leak result |
Use inspection methods for the questions they can answer
Visual examination records seam continuity, surface condition and accessible geometry. It is a useful screen but cannot establish internal fusion or prove hermeticity. Representative sections assess penetration and local weld structure. Package leak testing checks whether gas crosses the tested boundary under the specified conditions.
Use the laser weld quality inspection guide to coordinate these checks. Retain location information so that a failed leak test can be compared with the start, corner and closure records rather than only a general photograph.
For medical device enclosures, welding and leakage results are inputs to the manufacturer's broader product verification. They do not by themselves establish suitability for implantation or regulatory compliance.
Prepare a useful sample evaluation request
Send material identities, drawings, surface preparation details, internal component restrictions, the proposed inspection criteria and representative parts. Include known fit-up variation rather than supplying only the best-fitting samples. Ask for records that connect each trial condition to seam observations, sections and leak-test results.
JMLASER can discuss sample evaluation and the equipment configuration needed for the proposed process. Any target for leakage, atmosphere, cycle time or production yield remains project-specific until supported by qualification evidence.