Watts Current

All of Watlow's marketing resources are using the VOC process to learn more about the unmet needs in targeted markets. But one industry that will truly benefit from the VOC process is life sciences.

The markets in the life sciences industry offer a broad array of applications and requirements.

In order for Watlow to properly understand and serve this industry, the company placed an emphasis in VOC activities. Watlow has already learned quite a bit through the VOC process and determined products that will help solve industry challenges.

Examples of some of these products include:

Thick film heaters are ideal for applications such as gas chromatography injectors and detectors, mass spectrometer sources and differential scanning calorimeters where precision controlled heating, clean operation and rapid thermal response is required.

Watlow's flexible heaters can be adapted to a broad range of custom forms and shapes when temperature requirements are less than 250°C (482°F). These heaters are well suited for the diversity of form needed to heat the variety of component shapes used in the market.

FIREROD^® cartridge heaters can easily be designed into high mix/low volume instrument applications due to standard forms. They have the ability to pack a lot of power into a small package, an important feature in an industry where miniaturization is a common trend.

Watlow's tubular heaters are a cost effective and thermally efficient way to heat liquids and gasses in application-specific analyzers, recirculating baths and environmental ovens.

Standard DIN temperature controllers can easily be incorporated into OEM instruments where they do not have sufficient volume to justify designing and manufacturing their own embedded temperature control circuits.

ENVIROSEAL RTD's cold end seal provides extreme protection from salt water, motor oil and chemicals such as bleach, ammonia and boric and nitrous acid, which would be extremely useful in the analytical and medical applications. There is a wide sensor temperature rating and the ENVIROSEAL is perfect for a wide variety of applications, including refrigeration or condensation units, food processing, industrial ovens, medical research, packaging equipment and environmental control systems.

Watlow's heated parts, such as thick film and cast-in heaters, can reduce the number of components in the OEM assembly which is beneficial as OEM's want to focus more on systems integration, systems test, applications development and service and less on vertically integrated manufacturing optimization.

Watlow recently developed syringe heaters specifically for the medical injection market. Syringe heaters are made of clear polycarbonate material and sized to "snap" onto the outside of the syringe. This transparent construction allows the technician to easily view the syringe fluid level as well as monitor for air bubbles. By housing a custom control as part of the syringe handle these heaters can warm the contract media to precise temperatures.

Kapton^® heaters are an ideal choice when heating components of complex geometries. The heaters can be designed "origami-style" to fit the contour of a precise shape. The Kapton^® material will not effect sampling tests by outgassing and the surface is easily cleaned with most cleaning materials. Watlow's ceramic fiber heaters are being used to meet the high temperature demands of analytical process instruments.

For over 80 years, Watlow successfully partnered with thousands of customers for design and manufacturing services. Customers use Watlow's thermal expertise to support applications across many industries such as semiconductor manufacturing, plastics processing, foodservice equipment, life sciences and more.

Watlow's goal for the next 80 years is to understand its customer's unmet needs and as a result, provide value-added services in tandem with world class technology advancements. VOC is a scan for requirements and unmet needs. The information will be translated into products and services targeted at attractive markets. Watlow has always listened to its customers, but in the past this has been an informal process. The company implemented a formal VOC process in June 2003 and has already conducted almost 100 VOC listening sessions.

"Over the next year, you may be contacted by someone at Watlow regarding how we can serve you better. It's not to say a current challenge or product isn't important but this will be a different kind of call. We want our customer's opinion on how to better meet overall needs," said Dan Sparks, strategic marketing director.

"Listening to customer needs has to be embedded into the very fiber of how Watlow conducts business, day in and day out. Watlow is investing significant resources to create this environment. VOC is the way we want to interact with our customers," added Sparks.

For questions concerning the VOC process, please contact a Watlow representative.

For years, manufacturers in the life sciences industry struggled to get the most out of their tubular and silicone rubber heaters. Although these older devices have been improved, they still burden designers with many of the problems and limitations that have been hampering product development for years. Today's medical devices need higher watt densities, custom distributed wattages, faster response times and lower profiles. And the older devices are falling short.

Thick film heaters provide an effective alternative. Introduced for new equipment applications in 1997, they deliver heat with fast response rates, uniform heat densities and take up little space. Thin film heaters are also available but their power ratings are much lower.

Building In Layers
Thick film resistance heaters are built in layers. The base substrate can be either 430 stainless steel, aluminum oxide, aluminum nitride or quartz with layers of ceramic metal films sintered on at high temperatures. The layers are a sandwich of a glassy dielectric material, a metal resistor and an overcoat dielectric layer on top. One advantage of this technology is that designers can vary the heat output across an entire working surface, so they can correct most temperature uniformity problems generated by conventional heaters.

Despite their name, thick film heaters have a low profile that is useful when space is a premium. And because the substrates can be thin, they offer superior heat transfer with response rates as fast as 45 degrees Fahrenheit per second, depending on application.

Thick film heaters are a relatively new heater technology, so manufacturing processes available typically are not conducive to generating the lowest cost heater option at higher manufacturing volumes. Fortunately, thick film heaters often offset higher costs by replacing several thermal components with one heated part.

The new heaters are used in life science applications ranging from pharmaceutical manufacturing, where thick film designs help more tightly control process variables when making drugs to refining biological samples for analytical testing. Determining whether or not thick film heaters are suitable for a particular application depends on several variables.

The heaters are best suited for applications that require uniform heat across a surface. The flexibility of printing heating circuits in many thick film arrangements lets designers use individual or multiple zones to distribute heat.

For example, an analytical-equipment manufacturer needed a better heater for a biological sterilizer. The sterilizer originally used a Kaptonš heater glued to the equipment. The heaters occasionally came partially unglued because of high temperatures. As a result, heat transfer wasn't uniform and drove the heater to failure. To solve the problem, the manufacturer replaced the Kaptonš heaters with parts that had the thick film heater built right onto equipment surfaces.

The switch significantly increased the sterilizer's mean time between failure. In addition, because thick film heaters more uniformly distribute power, the sterilizers' temperature uniformity improved from 3.6 degrees Fahrenheit to less than 0.9 degrees Fahrenheit, which is critical to accuracy.

The new heaters also work well in limited space. With substrates as thin as 0.035 in. and a sintered glass thickness of 0.002 in., thick film heaters are thinner than most other designs, yet can be safely operated at watt densities double that of silicone rubber and Kaptonš heaters. Available watt densities range from 5 to 125 W/in2 depending on application and temperature. And the maximum operating temperature is 1022 degrees Fahrenheit.

Applications requiring fast response rates can also benefit from thick film heaters. The base or substrate for thick film parts is usually 430 stainless steel, aluminum oxide, aluminum nitride or quartz. The heaters can have 2D shapes as small as 0.5 in. wide and as large as 48 inches. Cylindrical units can have IDs ranging from 0.25 to 2.5 in., with lengths from 0.5 to 5.0 in. Wattage specifications are determined by the surface area available to each heater.

A few applications present challenges. For example, thick film may not be best for immersion heaters. Isolating the heating surface and its terminations creates concern over possible electrical hazards. However, thick film designs may be applied in a way that eliminates the need for direct immersion.

Ceramics are an alternative to stainless steel. Ceramics have relatively low thermal expansions, high dielectric strength and dimensional stability and tolerate high temperatures, making them a preferred substrate for more demanding applications such as gas chromatography.

Alumina is the most widely used substrate due to its chemical resistance, relatively low cost and stable physical properties. It's easy to fabricate into a range of shapes and will remain strong at high temperatures. Aluminum nitride, another ceramic, has high thermal conductivity, making it an excellent choice for devices needing fast response or precise and uniform temperatures. On the downside, custom shapes in aluminum nitride are expensive and difficult to fabricate.

Into the Future
Several other substrate materials are in development. Two of the most promising include aluminum and 304 stainless steel. And a new polymer-based film is in beta testing. The film can be applied to aluminum and copper which will transfer heat exceptionally well, meaning less temperature differentiation across a heated part. They are also easily machined. When available as a substrate, 304 stainless steel will provide a lower cost alternative. This material is less expensive than 430 stainless steel and is more readily available, making it a good choice for lower-cost applications.

Challenge:
The customer's initial design was a sandwiched assembled block containing coiled tubing and bonded silicone rubber heaters. This design had several performance issues including fluid contamination and corrosion as well as leakage throughout the fluid path. In addition, the bonded silicone rubber heaters on the aluminum plates had poor heat transfer, which caused inadequate temperature control. The design required custom assembly and the purchase of numerous parts, which resulted in additional customer time, effort and cost.

Solution:
Watlow converted the existing design to a one-piece cast-in aluminum construction utilizing tubular elements. Watlow's design significantly improved heat transfer and eliminated the corrosion and leakage problems. Alodine, a special protective external coating applied around the outside perimeter of the aluminum castings, reduced contaminants from the cast surface.

Watlow also facilitated the addition of customer-specified sensors, switches, wiring harnesses and electrical enclosures, delivering a ready-to-use product. This value-added assembly eliminated the time required for the customer to install and purchase 17 separate parts, reducing overall cost and effort.

The customer was pleased with Watlow's solution and integration capabilities. The cast-in solution enabled Watlow to migrate the solution to other assemblies in the customer's facility currently utilizing silicone and cartridge heaters.

In making hybridizing membrane incubators, the company was experiencing reliability problems with their temperature controllers and contracted Watlow for information on a new controller.

Solution:
A Watlow sales engineer spent a week analyzing the thermal system with a chart recorder and reviewed the data with a product engineer at Watlow. Together they specified the correct control parameters, but also concluded a new controller was not the complete solution. The Watlow Sales Engineer also recommended changing from the original high-mass heaters to lower-mass, fast-responding flexible heaters. This change not only performed up to design objectives, but consumed less power, too.

The new thermal system was then tested for several months to verify and quantify the results. The Watlow temperature controller and heaters outperformed the customer's initial performance criteria so well, Watlow was given the opportunity to provide the temperature sensor as well.

Ultimately solving this application problem became a redesign issue versus supplying a better component. Watlow's thermal system solution saved development cycle time by providing data about the original thermal system along with stock controllers and heaters for testing. To effect final system implementation, Watlow offered testing, engineering support, agency approved products and a special emergency stock arrangement.

To quote the customer: "Because of your (Watlow's) knowledge of the complete thermal system and depth of quality products, we have the confidence to rely on Watlow for our heater and controller needs."

This confidence in Watlow has assisted in drastically reducing the research time and testing on their current thermal system projects.