Laser Welding for Medical, Dental MFG., Mold Repair; Low Heat Distortion

Advantages of Laser Welding:
• Ability to Join Dissimilar Materials
• Low Heat Input & Low Thermal Distortion
• Filler Metal Welding for Positive Welding
• Faster Weld Rates
• Does Not Need to be Performed In a Vacuum
• Welds Magnetic Materials

Highlights At a Glance:
• AutoFocus System
• Motor movements in X/Y/Z & R
• Auto Teach Mode
• Low Oscillation Due to High
• Quality Rail System

HTS Nd:YAG, Pulsed

Process Welding Systems has enjoyed an excellent reputation for over 15 years with its product line of welding equipment for Plasma and TIG welding. With a mission of providing our customers the best technology available PWS is now offering Laser Welding. The recent advancements in Laser technology has made laser welding a very viable manufacturing process that is a natural extension of our micro welding expertise. When high quality welds are required our weld lab can evaluate your application with laser, plasma or TIG.

Process Welding Systems, Inc. has partnered with O.R. Laser Technologies, Inc. of Elk Grove Village, IL to offer a line of N:YG lasers. In addition to purchasing a 160 watt laser for our lab, PWS offers 120, 160, and 200 watt versions of the HTS laser welder. PWS will provide full sales, service and support for units sold by PWS.

LRS Nd:YAG, Pulsed

This laser leaves nothing to be desired when it comes to working on small to medium sized molds, we offer an extensive range of accessories for all of your laser welding needs. A unique feature are the two Z-axes that come standard. The processing table has a load capacity of 550lbs.

Whether you wish to apply common metal alloys found in tool and mold construction, or aluminum, copper or titanium, the laser capacities in the LRS series are optimally designed for welding. Units range from 50 – 160 Watts.

We also have the right solutions for automated laser welding jobs. CNC control, which is available as an option, and the autofocus system keeps the lasers focal point constant for laser welding for small batches or mass production.

The Difference Between Micro- Plasma and YAG: Laser Welding For Small Parts

YAG: Laser Welding

An acronym for yttrium- aluminum-garnet, the YAG laser produces short-pulsed, high- energy light beams to weld metals. This laser may also be called a neodymium-YAG or ND -YAG laser. A laser type using an infra red wavelength of 1064 nanometers. The laser material is neodymium. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates.

Laser beam welding has high power density resulting in small heat- affected zones and high heating and cool- ing rates. The spot size of the laser can vary between 0.2 mm and 13 mm, though only smaller sizes are used for welding. The depth of penetration is proportional to the amount of power supplied, but is also dependent on the location of the focal point: penetration is maximized when the

focal point is slightly below the surface of the workpiece. A continuous or pulsed laser beam may be used de- pending upon the application. Milliseconds long pulses are used to weld thin materials such as razor blades while continuous laser systems are employed for deep welds. LBW is a versatile process, capable of welding carbon steels, HSLA steels, stainless steel, aluminum, and titanium.

Micro-Plasma Welding Process

Plasma arc welding (PAW) is an arc weld- ing process similar to gas tungsten arc weld- ing (GTAW). The electric arc is formed be- tween an electrode (which is usually but not always made of sintered tungsten) and the

work piece. The key difference from GTAW is that in PAW, by position- ing the electrode within the body of the torch, the plasma arc can be sepa- rated from the shielding gas envelope. The plasma is then forced through a fine-bore cop-

per nozzle which constricts the arc and the plasma exits at the orifice at high velocities (approaching the speed of sound) and a temperature approaching 20,000 °C. Plasma arc welding is an advancement over GTAW.

The Advantages of Laser Welding

  •   Precise Energy Input
  •   Minimum Heat Effected Zone
  •   The Weld is Cool to Touch Seconds After Welding
  •   Welds Can be Sited in Close Proximity toSensitive Components or Structures
  •   Non-Contact Welding
  •   Precise Control of Laser Beam Pulsing Profile
  •   No Contamination From Tungsten Particles
  •   No Heat Discoloration
  •   Welds Magnetic Materials
  •   Low Heat Distortion
  •   No Need for Elaborate Heat Sinks
  •   High Travel Speeds
  •   Highly Reproducible Welds
  •   Advantages of Laser Welding in Tool & Die Repairs

    ____________________________________________________________________

    The Advantages of Plasma Welding

    •   Thin Wire Deposition Using Microscope for Positioning
    •   Ability to Weld in Deep Holes and Cavities
  •   Protected electrode, offers long times before electrode maintenance (usually one 8 Hr Shift)
  •   Low amperage welding capability (as low as 0.05 amp)
  •   Arc consistency and gentle arc starting produce consistent welds, time after time
  •   Stable arc starting and low amperage weld- ing
  •   Minimal high frequency noise issues, HF only in pilot arc start, Pilot Arc Used to Transfer Main Arc
  •   Arc energy density reaches 3 times that of GTAW. Higher weld speeds possible
  •   Weld times as short as 10 msecs (.01 secs
  •   Energy density reduces heat affected zone, improves weld quality
  •   Voltage of Arc Remains Constant WhenLength of arc Changes
  •   Diameter of arc chosen via nozzle orifice
  •   Lower Cost Than Laser

The Cost Differences Between Laser and

For laser Welding Systems the Prices Vary According to the Power Needed. For Thin Materials Usually Low Power YAG Lasers are Sufficient. Low Power YAG Lasers Range in Size from 55 Watts to Several Hundred Watts. Class 1 Lasers come with a Safety Enclosure Around Them. Class Four Lasers are Open. YAG Low Power Lasers Range in Price from $35K to $110K. Higher Wattage Lasers in the Kilo Watt Range Can Cost Several Hundred Thousand Dollars.

Micro-Plasma Welding Systems are Categorized by Welding Current Output. Most Micro-Plasma Welders On the Market have Outputs Be- tween 0.5 to 150 amps. Micro-Plasma Applications use a Welding Current Between 0.5 to 30 amps. In some Cases However Higher Welding Current is Needed. Depending on What is Needed for the Application the Prices of Micro-Plasma Welding Systems can Vary Be- tween $10K for a Manual System, to $17K for a Programmable System.

 

Special points of interest:

  •   Short Definition of YAG: Laser and Plasma
  •   Process Advantages
  •   Cost Differences

Plasma Welding Summary

The plasma welding process was introduced to the welding industry in 1964 as a method of bringing better control to the arc welding process in lower current ranges. Today, plasma retains the original advantages it brought to industry by providing an advanced level of control and accuracy to produce high quality welds in miniature or precision applications.

The plasma process is equally suited to manual and automatic applications. It has been used in a variety of operations ranging from high volume welding of strip metal, to precision welding of surgical instruments, to automatic repair of jet engine blades, to the manual welding of kitchen equipment for the food and dairy industry.

How Plasma Welding Works:

A plasma is a gas which is heated to an extremely high temperature and ionized so that it becomes electrically conductive. The plasma arc welding process uses this plasma to transfer an electric arc to a work piece. The metal to be welded is melted by the intense heat of the arc and fuses together.

The system requires a power supply and welding torch. In the torch an electrode is located within a torch nozzle having a small opening at the tip. A pilot arc is initiated between the torch electrode and nozzle tip. Gas is fed through the nozzle where the pilot arc heats the gas to the plasma temperature range and ionizes it. The gas emerges from the nozzle in the form of a jet, hotter than any chemical flame or conventional electric arc. The main welding arc transfers to the work piece through this column of plasma gas.

Plasma gases are normally argon. The torch also uses a secondary gas, argon, argon/hydrogen or helium which assists in shielding the molten weld puddle thus minimizing oxidation of the weld.

By forcing the plasma gas and arc through a constricted orifice, the torch delivers a high concentration of heat to a small area. With suitable equipment the process produces exceptionally high quality cuts on a variety of materials.

Plasma Welding Features & Benefits:


F: Protected electrode

B: Protected electrode allows for less electrode contamination. This is especially advantageous in welding .materials that out gas when welded and contaminate the unprotected GTAW electrode.


F: Length of arc benefit due to arc shape and even heat distribution

B: Arc stand off distance is not as critical as in GTAW. Gives good weld consistency. No AVC needed in 99% of distribution applications, sometimes even with wirefeed.


F: Arc transfer is gentle and and consistent

B: Provides for welding of thin sheet, fine wires, miniature components where the harsh GTAW arc start would damage the part to be welded.


F: Stable arc in welding

B: Reduces arc wander. Arc welds where it is aimed. Allows and arc starting tooling in close proximity to weld joint for optimum heat sinking.


F: Minimal high frequency noise in welding

B: Minimal high frequency noise once pilot arc started, thus plasma can be used with NC controls. Another benefit lies in welding applications involving hermetic sealing of electronic components where the GTAW arc start would cause electrical disturbances possibly damaging the electronic internals of the component to be welded.


F: Arc energy density reaches 3 times that of TIG

B: Causes less weld distortion and smaller welds. Gives high welding speeds


F: Weld times as short as .005 seconds

B: Extremely short and accurate weld times possible for spot seconds welding of fine wires, accurate weld times combined with precision motion devices provide for repeatable weld start/stop positions.


F: Equipment options offer up to 10,000 Hz

B: Offers a wide range of pulsing options for varied, pulsing applications.


F: Low amperage art welding (as low as 0.05 amp)

B: Allows welding of miniature components or good control in downsloping to a weld edge.


F: Arc diameter chosen via nozzle orifice

B: This feature assists in predicting the weld bead size.


Plasma Welding Features, Benefits & Applications

Features & Benefits:

P Protected electrode, offers long times before electrode maintenance (usually one 8 Hr Shift)

L Low amperage welding capability (as low as 0.05 amp)

A Arc consistency and gentle arc starting produce consistent welds, time after time

S Stable arc in arc starting and low amperage welding

M Minimal high frequency noise issues, HF only in pilot arc start, not for each weld

A Arc energy density reaches 3 times that of GTAW. Higher weld speeds possible

W Weld times as short as 5 msecs (.005 secs)

E Energy density reduces heat affected zone, improves weld quality

L Length of arc benefit due to arc shape and even heat distribution

D Diameter of arc chosen via nozzle orifice


Metals that plasma can weld include stainless, heat resistant and other steels, titanium, Inconel, Kovar, zircalloy, tantalum, copper, brass, gold and silver.


Applications:

The benefits of the plasma process offers two prime benefits: Increased welding speed and improved weld quality. Plasma is excellent for welding wires, tubes, strips, sheets, and all miniature, medium and large components requiring precision welding. In many applications, many of the unique advantages of plasma combine to benefit the welding process.

Wire Welding: The plasma process can gently yet consistently start an arc to the tip of wires or other small components and make repeatable welds with very short weld time periods.

Strip Metal Welding: The plasma process provides the ability to consistently transfer the arc to the workpiece and weld up to the edges of the weld joint. In automatic applications no Arc Distance Control is necessary for long welds and the process requires less maintenance to the torch components. This is especially advantageous in high volume applications where the material outgases or has surface contaminants.

Sealed Components: Medical and electronic components are often hermetically sealed via welding. The plasma process provides the ability to;
1. Reduce the heat input to the part
2. Weld near delicate insulating seals
3. Start the arc without high frequency electrical noise which could be damaging to the electrical internals

Precision Instruments: Many instruments require welds of great accuracy. Plasma welding, with its control and precision, provides the ability to make these critical welds.


Other Plasma Welding Applications

Surgical Instruments, Needles, Wires, Light Bulb Filaments, Thermocouples, Probes, Pressure and Electrical Sensors, Bellows, Seals, Cans, Enclosures, Microswitches, Valves, Electronic Components, Motors, Batteries, Miniature Tube to Fitting/Flange, Food and Dairy Equipment, Tube Mill Applications, Tool Die & Mold Repair.


Comparison of GTAW & Plasma Welding Energy Input

Test Parameters: Manual welding, no clamping device, Cr/Ni steel, 0.102″ thickness; all values determined with measuring instruments.

GTAW: 125 Amps 12 Volts 10.24 I.P.M.
Plasma: 75 Amps 18 Volts 13.38 I.P.M.
Heat Input: V x A x 60


Speed in cm/min

GTAW: 12 x 125 x 60


Speed in cm/min

= 3.46 KJ
Heat Input: 18 x 75 x 60


34 cm/min

= 2.38 KJ

In addition to the fact that a higher weld speed is possible, the lower heat input brings the following advantages:

 

  • Less distortion
  • Less stress in welded component
  • Less tempering color with Cr/Ni steels
  • Lower risk of damaging any heat sensitive parts adjacent to the weld joint