Frequently Asked Questions

for DCC Corporation

Why use capacitive discharge welding to create a thermocouple sensor?: Welding produces a mechanical and electrical connection that creates a solid sensor starting point of zero electrical potential difference and zero temperature difference between the two thermocouple sensor wires. Capacitive discharge welders release energy extremely quickly, resulting in a very small heat affected zone.
How is the temperature difference measured via a thermocouple sensor?: A temperature gradient along the wire will produce a voltage gradient proportional to the temperature difference between the hot and cold ends of the wires.
How is the temperature difference related to the voltage difference measured at the open end of a thermocouple sensor?: At the open end of a thermocouple wire pair, the voltage difference present between open ends will be proportional to the temperature difference between the shorted ends and the open ends of the sensor pair for the particular alloys in the thermocouple wires.
Why is a small, welded bead used to connect the thermocouple wires?: The function of the bead is to create an identical thermal and electrical environment at the wire ends. The thermocouple output is not produced by the bead, but by the temperature gradient along the wires themselves. Thin wires and small welded beads produce a quick response.
How is a temperature range calculated using a thermocouple sensor?: The nonlinear relationship of sensor volts produced per degree temperature shift along the sensor wire pair is temperature range dependent. Tables, compensating circuitry, or algorithms are used to produce accurate results for corresponding temperature range differences for each wire pair type.
What factors are considered when choosing the materials for a thermocouple sensor?: Standard alloy pair wire and insulating materials are chosen to match the measured temperature range, maximum temperature, and environmental conditions expected. Time response and durability affect the choice of wire size. Some materials will melt at high temperatures and some insulating materials are not waterproof.
What are the benefits of having my own thermocouple welding capability?: Having your own thermocouple welder saves time, costs, and offers convenience. You can create free standing beads or directly welded thermocouple sensors using standard wire of any length, allowing for quick changes, additional junctions, and experimental set-ups on a “when needed” ‘where needed’ basis. Installation materials can be recovered and reused.
Can very thin thermocouple wires be welded?: For fine wires, the miniature pliers are needed. The teeth on the larger pliers allow fine wire to slip or twist and poor contact with the pliers allows arcing to occur at the jaws instead of the wire ends. Freestanding beads can be created with modified techniques. Twirling the ends lightly together and then sweeping the wires across the carbon block with the firing button depressed will generate a smaller spark. Too large of an arc can vaporize the wires. Direct attachment of fine wires to surfaces is best accomplished by pressure or spot welding wires 30 gauge or finer. The HotSpot welders support this technique.
Can thermocouples be attached to materials such as aluminum or brass?: Welding to materials that such as aluminum, copper, titanium, zinc alloys and brass can be accomplished. These materials are difficult to work with because of their high conductivity, low melting temperatures, and easy oxidation. The size of wire and thickness of base materials impact results a powerful arc can create a hole through thin materials. Successful bonding to such materials can include preforming a beaded junction, and lightly striking the thermocouple onto the surface to reduce the amount of molten material expelled by the arc. Flooding the well spot with a light flow of protective gas like argon can also reduce oxidation and produce a better weld.
How does the HotSpot welder work?: The HotSpot welders have the same general design and operation. When the HotSpot is turned on, the internal large storage capacitors are charged to the level set by the control on the front panel. The ground electrode can be connected to the carbon block for freestanding welds or connected to a base material by magnet or clamp (not included). The wire or item to be welded is held in the attachment pliers. When the operator depresses the firing switch, this discharges the stored energy through the attachment cable and causes and arc at the contact point with the base material. The arc releases a burst of heat to locally melt both the wire and base, producing a fusion weld.
How long does it take to create a thermocouple weld?: A thermocouple weld can be made in just a few seconds. The HotSpot welders can be recharged in under 10 seconds and are then ready to create the next weld.
Where are HotSpot welders used?: The HotSpot welders are suitable for Field use, where their small size and portability provide the flexibility needed; Shop use, where the size or shape of the piece to be treated dictates that temperature sensors or fixturing items are directly installed on the piece; and Lab use, where the versatility of the units support immediate installation, quick changes, and multiple experimental set-ups.

Thousands of HotSpot units have been sold since the early 1980s. They are used in the Aerospace, Energy, Manufacturing, and Transportation industries. The HotSpot line of welders supports research activities in private laboratories as well as universities and government agencies.
Which HotSpot capacitive discharge welder should I buy?: Our HotSpot capacitive discharge welder line has three models to meet a variety of needs. All of the welders are durable, easy to use, and portable. The original HotSpot is versatile with its small size and internal battery power making it easy to use anywhere. The HotSpot II is a dual range high-energy unit that has the versatility for fine control as well as the power capability for heavier wire, pin, and light spot welding. The HotSpot Plus doubles the power range of the HotSpot II and can weld studs lighter than 1/4-20. A weld initiation control is in the Plus attachment handle and an optional foot pedal is available, creating the ability for single handed operation. With a range of power levels and price points, choosing the right model is easily determined by your application.
Who makes the HotSpot welder?: The HotSpot welders are designed, manufactured, and sold by DCC Corporation. They are assembled in New Jersey with US supplied and manufactured parts. We work with a limited number of distributors and resellers for sales of new equipment.
Can I buy a used or refurbished unit?: DCC does not sell refurbished units and only repairs units under warranty. Used units are listed on eBay and other resale sites by private individuals. DCC cautions these units may have damage due to neglect, abuse, missing or worn components. Non-working units returned to DCC are e-cycled or used for internal development purposes. They are not sold for refurbishment.