Automotive - Fuel Injectors
Modern fuel injectors for gasoline, diesel, and gaseous fuels all incorporate laser welding to improve quality and maximize production throughput. Fuel injectors are extremely precise devices that require controlled hermetic welds to ensure their operation and safety but the joining operation is much more than that. Any extra heat or distortion will produce fuel delivery rate or spray pattern anomalies resulting in scrap. Distortion can also affect static leakage rates that are tightly controlled for environmental limits.
There are many different alloys used in these injectors. Ferritic stainless steels such as 405, 430, 430F, and the Chrome Core family of alloys are employed where magnetic induction is needed for solenoid action. For low wear components that are non-magnetic such as guide tubes and out tubes, 305SS is used. For medium wear components that are non magnetic such as armature guides and seats, 416SS is the typical choice. Finally, because of its hardness, 440C is used for valve seats and valve seal balls.
Weld times of 0.2 to 0.75 seconds are typical for most gasoline injectors with laser power of 250-500W and fiber optic delivery. Part-to-part times for these welding and assembly machines are in the 3-5 second range. Time-Share Multiplexing to send the output from one laser to multiple workstations can be used but high-speed assembly machines don't often use them due to the asynchronous nature of separate machines. Energy-Share, however, is often used on alignment sensitive components. Two-Way Energy-Share takes the output from the laser and produces a 50:50 split between two fiber optics to make simultaneous welds 180 degrees apart so the weld forces are equal and opposite to maintain concentricity of the assembly.
Most welds are best performed with Super Modulated CW Nd:YAG lasers because of the short time cycles and the metallurgy of these stainless steels and some of the free-machining grades that are used. Super Modulation of the laser's output improves the welding speed or penetration up to 40% when compared to CW-only operation. This greatly reduces heat input and distortion.
Typical lasers that have been used for this application
JK401SM & JK501SM
Lamp-Pumped Nd:YAG, 400 & 500W, 800 & 1000 with SuperModulation
JK802 & JK1002
Lamp-Pumped Nd:YAG, 800 & 1000W, 1600 & 2000 with SuperModulation
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