by Dr. David Ward, engineering director, Molteni Technologies
This paper examines the performance of a domestic oven by developing a simple model to macroscopically describe the relative heat and mass transfer involved, followed by a closer look at the calculation of the thermal mass depending on food ingredients and mass loss due to evaporation.
The appliance industry is making demands, and switch suppliers are feeling the pressure. OEMs are pushing down pricing, partly by going to new, lower-cost sources. Established switch suppliers have responded by redoubling efforts to keep their costs down, not least by changing manufacturing locations.
According to Steve Hugener, marketing manager, Cherry Electrical Products(Pleasant Prairie , WI , U.S. ), "While overall switch industry capacity has been fairly flat, OEMs have become more adept at accessing worldwide capacity, especially from Chinese manufacturers. In addition, many of the traditional U.S. switch manufacturers are now taking advantage of low-cost switch assembly in China , while still offering local design and applications support in the U.S. This seems to provide the appliance producers with the best of both worlds."
Low prices and manufacturing changes have helped stoke mergers, spinoffs, and other status changes in the switch industry. "Mergers and acquisitions within the switch industry can provide appliance OEMs with some benefits in terms of potential vendor reduction," points out Mr. Hugener, "but only if the resulting switch conglomerate is coordinated enough to deliver on these potential efficiencies."
Tyco Electronics (Harrisburg, PA, U.S.) has introduced a new line of power rocker switches in three sizes. Each size fits into different industry standard panel cutouts (13 x 19, 14 x 28.5, and 25 x 28.5 mm). Within each size, a number of options are available, including a variety of termination methods, illumination, single/double pole capability, and special markings. The switches are dust resistant and available with secondary rocker colors. Applications include commercial food handling and storage equipment, vacuums, office equipment, power tools, medical equipment, lighting, and small appliances.
As Martin G. Leslie, product manager, Therm-O-Disc, Inc.( Mansfield , OH , U.S. ), views it, "In general, it's not uncommon for a new company to come out with some sort of competing product. Most of the time, it's an Asian house, and the overall effect of new entrants is, of course, to make the market more and more competitive."
But he adds, "While price seems to be the biggest concern for most producers, it's understood that good quality, delivery, and service (both technical and logistical) are absolutely critical to stay in the game."
Adds Ugo Baldereschi, marketing manager of Signal Luxin Cornaredo , Italy : "The focus of switches has moved to the accessory activities that go with the assembly of appliance components. The assembly of switches and their wiring is an important cost, so it's possible to spend much time and money on the engineering of integrated control systems that allow for the installation of an entire control console.
"Of course, an integrated system must necessarily be customized to the application and to the customer. It is not possible, for example, to produce a complete control system for a water cleaner and believe it could possibly be useful for a vacuum cleaner! It's instead more likely that a customer that manufactures water cleaners needs a system that is somewhat similar, but is produced in a totally different way! Therefore, a new role is being defined for switch manufacturers where the R&D units assume a prevailing role. The question to ask is if the organizational structure and traditional culture of R&D units with appliance companies can operate in this new situation."
With prices at what some switch suppliers view as rock bottom, companies work to differentiate themselves in areas other than price. Regardless of where manufacturing takes place, they emphasize the value of maintaining a close customer connection. As Therm-O-Disc's Mr. Leslie tells APPLIANCE, "The best thing an appliance company can do is involve the supplier as early as possible. If we understand the underlying customer needs, we can help recommend the right product - whether we supply it or not. I think most suppliers feel this way today."
"As a supplier, to remain competitive we have always tried to build a certain type of relationship with our customers based on an ongoing flow of information," offers Henry Burgess, sales assistant at Amisco s.r.l. ( Paderno Dugnano , Italy ). "We make sure that this condition flourishes between us, even at an early stage of the project. The aim is that we can develop and make exactly what the producer needs, no more and no less. In this way we can optimize the product configuration not only for the commercial aspects, but also and primarily for the manufacturing process. We have found that this approach can save us large amounts of time and money, which is a benefit to us and to our customer.
"This philosophy is an integral part of the Amisco DNA," Mr. Burgess continues. "We must always bear in mind that the customer wants something that does more and costs less. To this end, we must not only give the customer a product but we must give him service. The level of service that we give determines also the success or failure of the project."
"Getting more for less, low cost, reliability - these continue to be key for appliance switches," says Ann Fagan, Alcoswitch product manager, Tyco Electronics( Harrisburg , PA , U.S. ). "And, because of the variety of challenging environments in which their switches are used, appliance OEMs typically need a higher level of interaction. As an experienced player in the industry, we already have the coverage in place."
Saia Burgess USA Inc.( Vernon Hills , IL , U.S. ) promotes the development of innovative modules in a cooperative effort between itself and its customers. It says individual phases of the process can be carried out by itself or shared partially or fully with the customer. The customer can benefit from the supplier's know-how and the latest resources for development and production. Its specialized knowledge is said to result in a high potential for optimization. Since everything is from one source, there is more likely to be a smooth passage from development to production. Another advantage: because of reduced demands on the customer's development department, there is a savings in time and better exploitation of the company's own resources.
Mr. Baldereschi of Signal Lux says that electronics in switches offer new opportunities to lower costs. "The challenge exists in being able to turn this phenomenon into an opportunity. Often, the synergy between electronic solutions and electromechanical systems has allowed us to offer the most convincing and innovative solution to our customer. We believe that those who can use both types of technologies will always have an advantage."
Some suppliers differentiate themselves with value-added services. According to Ben Ho, Toneluck Electronics IndustrialCo., Ltd. ( Hong Kong ), "As a component manufacturer, there are two ways to help appliance companies to reduce device cost and their manufacturing cost. First, we reduce cost by continuous manufacturing process improvement. Second, we offer value-added services. Offering switch assemblies is a typical example. This can save the expensive manual assembly process in using our switches in the U.S. or Europe , by utilizing the lower labor cost in Asia .
"As an example, take a pressure switch for water heaters," he adds. "We first sold the microswitch to our customer in Europe . Our customer assembled the micro and made a complete pressure switch for water heaters. Today, we make the microswitch, build the complete pressure switch, and calibrate it according to the customer's specifications. It brings total cost down more than 30 percent by integrating all these assembly processes at our operation.
"Another example is a power switch for kitchen cooker hoods," he continues. "Previously the cooker hood makers bought the power switches from us, did the PCB assembly in-house or by a third party. It took about 10 weeks or more after placing the order for switches before the PCB was ready for the hoods assembly. Now cooker hood customers buy the PCB - with the switch assembled - directly from us. It takes less than 6 weeks for the tested PCBs to arrive at the customer's factory for hoods assembly. This not only saves cost, but significantly saves lead-time."
Observes Cherry Electrical Products' Mr. Hugener, "Switch manufacturers should aim to fully understand how their switches are being applied in the appliance. This opens the doors to lots of value-engineering possibilities, like optimizing the switch contact design to match the customer's requirements, or integrating brackets and panels to reduce the OEM's assembly cost. There is a trend toward more switch assemblies, mainly because switch manufacturers tend to be experts at flexible, low-cost light manufacturing, so they're often able to save the OEMs money."
John Sutherby, director of Marketing Communications, Switch Products, ITT Industries, Cannon ( Watertown , MA , U.S. ) sees a trend to more switch assemblies. "OEMs want the switch supplier to provide the switch with value-added options such as a bracket for mounting, leads and connectors attached, special colors to match other areas of the end product, and special markings on the actuator."
The surface mount, three-way B6J jog lever switch is said to be the first in the industry to offer confirming tactile feedback in all three directions (scroll up and down, and select). Its tactile feedback for push and scroll functions simplify operation. With an actuator 2.3-mm thick, its compact size allows high-density component mounting that reportedly is ideal for small hand-held devices. In addition, this Omron Electronics LLC (Schaumburg, IL, U.S.) switch accepts customer designed key-tops to match the switch's product design.
The CSE 15 uG (capacitive switch element under glass) is a capacitive momentary/latching switch with no mechanical parts that could lead to a functional failure due to damage, freezing, or wear and tear. The switch is actuated by touch or by simply approaching the surface under which it is mounted. Sensitivity of this Schurter Inc. (Santa Rosa, CA, U.S.) switch can be adjusted. For example, it is possible to operate the switch behind an overlay up to 20-mm thick - even when the operator is wearing gloves. Any non-conductive materials, e.g. glass, plastic, wood, ceramic, etc., may be used as a base for the overlay.
Switch reliability today is generally acknowledged as being quite good, but appliance environments can be challenging, points out Gregg Schreiber of TouchSensor Technologies, LLC (Wheaton, IL, U.S.). "Appliance producers are looking for switch technologies that work reliably in cold, hot, and humid environments. Beyond reliability, the appliance industrial designer also needs the switch to integrate smoothly with the rest of the user interface design," says Mr. Schreiber.
"Massive reduction in field failures is one big area where we help appliance companies reduce switch device costs," he continues. "Conventional switch technologies can have a service incident rate of nearly 1 percent in some applications. By implementing our keypads behind decorated glass or formed plastic, the OEM experiences the elimination of switch failures because the silicon chip is mounted behind the substrate and away from users or environmental abuse."
"The most important issue is ensuring that customers have selected a switch that will perform as required for the life of the appliance," cautions Cherry's Mr. Hugener. "Switches are quite inexpensive compared to the total value of the appliance, but designing in the wrong switch can create expensive problems down the road, and sometimes the distinction between the right switch and the wrong switch can be subtle."
Major Appliance Caution
While the trend in switch prices has been downward, due to new regulations there is the potential for higher prices for some switches. A new standard for household appliances, IEC 60335-1 4th edition, has new requirements on "resistance to heat and fire" in chapter 30. These are reportedly much stricter than those previously used.
"Of course an improvement in security is always good, but the consequences from the marketing point of view are immense," says Wolfgang Häußler, Marquardt GmbH ( Rietheim-Weilheim , Germany ). He observes that standard switches passing tests according to the international switch standards EN 61058 or UL 1054 are safe for an attended household appliance, but it could be that they are not safe for an unattended household appliance.
"Due to the price pressure on standard switches in the past, they were designed to the limit, and most of them won't be able to fulfill the additional requirements of the new IEC 60335," he says. "So the switch market of the future for unattended household appliances will be a different one than in the past. Standard switches designed for a broad application range won't be applicable to major appliances any more. The switch market for major appliances will develop to a special niche, fulfilling special requirements nobody in any other industry is willing to pay for. The special design and material we need for the IEC 60335 costs more and has no benefit for a manufacturer of office equipment, vending machines, vacuum cleaners, automotive, or any other customer."
Designed specifically for the white goods market, Duraswitch's flex circuit integrated thiNcoder(R) EZI 2.0 can function as a low-cost 5-bit encoder, 2-bit repeating Gray code, or selector switch.