Brewing Efficient,
Manufacturable Designs

DFMA software perks up design of water filters and coffee maker

—edited by Richard Mandel

Access Business Group, Ada, MI, develops, manufactures, and distributes a diversity of durable goods, including patented air filtration systems, and water treatment systems that use carbon and UV light technology for optimal health and taste benefits. The National Sanitation Foundation International has commended Access filtration system performance, and the Water Quality Association awarded Access a Gold Seal in 2000. 

Two years ago, ABG developed a high-end coffee maker to support a line of gourmet coffees. The resulting device, the Kahve Coffee Maker, is the only machine of its kind endorsed by The Society of Specialty Coffee Association (SCAA), a major trade group for the coffee industry. Special attention to temperature control and uniform coffee saturation achieves the taste benefits of maximum coffee extraction with pure water. “Coffee drinkers will purchase high quality coffee beans, but they now want sophisticated coffee makers to produce the richest possible taste,” says Rick Good, research scientist and process engineering group leader at ABG. 

DFMA improves design

Distinctive design features of the coffee maker include closely controlled water temperature — critical for best coffee brewing — and a motor to spin the brew basket for maximum saturation of the ground beans, rendering uniform coffee extraction. Initially the motor was at the base of the machine with an elaborate pivot and holding system that extended up through the unit. This system would turn an O-ring under the outer rim of the brew basket, spinning it quickly. Unfortunately, the large size of the required motor support and drive system made the planned unit appear bulky, which would not have supported the design team’s emphasis on light elegance. 

ABG studied the problem with Design for Manufacture and Assembly (DFMA) software, which provides a systematic means of examining the structural efficiency and overall manufacturability of a product. Design for Assembly (DFA) analysis helps engineers assess the contribution of each part as it relates to the cost efficiency and functionality of the whole design. Design for Manufacture (DFM) analysis enables designers and concurrent engineering teams to anticipate manufacturing costs early and to make informed trade-offs regarding the costs of producing multifunctional, streamlined designs. The company uses DFMA software from Boothroyd Dewhurst, Inc., Wakefield, RI.

DFMA helped reduce the part count of the motor assembly and led designers to reposition the motor higher on the machine, closer to the power destination. As a result, designers found that they could use a smaller Mabuchi motor that requires less power and maintains the sleek lines most consumers expect from luxury design. “The software systematically challenges engineering assumptions. In this case we were freed from a basic misconception that a motor had to be positioned at the base of the unit,” says Good. Through several design iterations, the team successfully reduced parts count, assembly time and cost. “Our main challenge, beyond creating flavor-eliciting features to meet our stringent product profile, was to design the coffee maker to be a streamlined, manufacturing-efficient product,” says Good.

A major goal of DFMA analysis is to determine the minimum number of parts necessary in a design. For ABG, DFMA is also integral to the ITM (Ideas to Market) process for benchmarking and brainstorming on issues related to product features and capabilities, manufacturability, and public health. Use of DFMA at the company typically begins at the preliminary bill of materials stage to establish a basis for comparing further revisions. For some durable goods, such as the Kahve coffee maker, they benchmarked existing units from manufacturers Krupps and Braun. These represented established competitors’ designs with price points comparable to the Kahve. DFMA analysis is an iterative process at the company, applied at the end of each design revision. “We use DFMA aggressively to challenge the design to become ever more efficient,” says Good. Each revision to the bill of materials is followed by a review and comparison with the last design. 

They applied three rounds of DFMA to the coffee maker design. The machine is a combination of original design and purchased components. The first round at the concept stage tested a preliminary bill of materials. The second round occurred in mid-product development after the motor was raised. The third round fine-tuned the design. The DFA software provides an objective rating of the design, called an index, that engineering teams use to measure development. The index number rises as the design’s assembly times and cost are lowered and parts are consolidated or omitted. This table indicates how DFMA helped reduce part count, cost and assembly time of the Kahve coffee maker:

Filtration design flows through DFMA 

Water and air filtration systems are a core product at Access. The company’s engineers recognized that using specially-filtered, temperature-controlled water in a coffee maker like the Kahve was one clear way to achieve better tasting coffee. 

Home water treatment systems are designed for installations on countertops or below sinks. Most ABG water filters use carbon block filtration, and recent technology adds UV-light disinfection for increased cleaning efficiency. The carbon-block water filter works in four steps. Untreated water flows into the outer filter chamber where a non-woven pre-filter removes large particulates. Pre-filtered water passes into a second area, where another non-woven pre-filter extracts smaller particulates, such as clay and sediments. Next, the central carbon-block filter removes very fine particulates, parasites, lead and certain chemical contaminants. Carbon, pre-activated with oxidizing gases at very high temperatures, attracts and binds certain chemicals as water passes through the porous carbon block. The filter surface may interact chemically with organic molecules, and electrical forces may result in an ion exchange or adsorption of the contaminant. This filter reduces many specific organic contaminants with relatively large molecules, depending on pore size and distribution. After the water is carbon treated, it flows through a tube to exit the filtration system. UV-light disinfection, in units so equipped, kills unwanted bacteria and virus organisms to greater than 99.9% purity level.

Good points out that beyond a demand for the best possible flavor, “the American consumer is increasingly concerned about relatively high water bacteria and contaminant levels.” Emphasizing taste and health, ABG maintains a small pore size for its carbon water filter, to remove the highest amount of particles. For similar reasons, the company stresses reliability of a sensor bulb that lights when the filter needs replacement. Standards of protection for public water sources vary greatly from one nation to the next, which must be taken into consideration for design and manufacture on an international scale. “Southeast Asia is a major growth sector, with high levels of large particles in the water,” says Good. “Therefore, Access currently uses DFMA to benchmark filtration systems and add a pre-filter to remove large particles without clogging the unit.” 

DFMA was used again on the filter design to reduce parts count and assembly time. The software guided the engineers to incorporate the holding chambers, carbon pressure vessel and UV-lamp vessel into a single piece. The UV-lamp was integrated into the carbon block, eliminating the need for a separate holding vessel. The following table summarizes results from five rounds of DFMA.

ABG retains DFMA benchmarks of all prior products for future comparison. The company is currently developing a new filtration unit for the U.S. market. As a next-generation device, it will be compared to the “parent” product. “We can look at outside competitors, but we view ourselves as our own competition,” says Good.

Initially, the Kahve was developed as a luxury coffee maker to use with advanced water filtration systems and to boost sales of a specific gourmet coffee line. Having fulfilled its supportive role, the Kahve Coffee Maker design is now available to manufacturers. “The design quality we achieved with DFMA, a high consumer demand for gourmet coffee, and our unique SCAA endorsement make the Kahve Coffee Maker extremely marketable,” says Good.

Boothroyd Dewhurst 
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