Process-Spanning Harness Design Approach
Sets the Pace for Productivity
By Nigel Hughes
Product Marketing Manager, Integrated Electrical Systems Division
Mentor Graphics Corporation

Harness makers who want to remain competitive and preserve margins must continually innovate in all areas of their business. Software design and simulation tools are cornerstones of harness design, and this class of tools has made tremendous technical strides in recent years, reshaping the design process. The information flow, from project inception to completion, is more comprehensive and contiguous than ever before. Commercial Off-the-Shelf (COTS) solutions increasingly are becoming the tool of choice for innovative harness design teams.

Figure 1 depicts a harness design flow as performed with the type of electronic design tools commonly used in the assembly industry. In a perfect world, such tools would merge input data such as wiring details, MCAD and configuration data, and component data, provide tools for design enrichment, and ultimately, create a flawless, ready-to-build harness design.

However, Figure 1 is a simplified view. What’s not shown is the effort that goes into resolving, or better yet, avoiding the issues that may arise at some of the inflection points in the process. Let’s take a look at some common pitfalls that can complicate the design process. 

§         Data re-use: Harness suppliers receive data from many sources, each requiring different naming conventions and policies. Harness suppliers often must manually adjust the data to enforce consistency.

§         Design changes: Revisions sometimes consume 80 percent of the total design effort. Lack of effective change processes can increase costs and introduce significant quality risks.

§         Proprietary tools: In-house design tools automate the harness engineering process, but the cost of developing and supporting these tools is high.

§         Costs: Harness vendors must fully understand the material and labor costs involved with their designs. Errors in commercial quotes can diminish profit margins or even turn them into losses.

§         Component data: Harness suppliers need to manage multiple component profiles, as component usage and the number of approved configurations varies.

§         Data continuity: Manual re-entry of evolving harness data may seem like the path of least resistance, but tight integration with PDM and MRP/ERP is essential to support recordkeeping and data re-use between engineers, departments, or companies.

Many of these uncertainties could be solved by the adoption of uniform, flexible design platforms that span the entire design process. Implementing consistent tools and processes can help companies manage their design information and propagate it efficiently from the earliest conceptual steps, right through to manufacturing and even service.

OEMs and their harness vendors have confronted these realities in diverse ways. Some continue to rely on their “point tools.” Some OEMs have developed their own drawing and data formats, and may require their suppliers to use specific tools. But these approaches have complications of their own, and can burden a harness vendor with multiple toolsets for multiple customers.

Leaders in the harness industry are adopting third-party (COTS) software solutions in an effort to boost efficiencies and avoid the cost of supporting proprietary platforms. A new generation of powerful COTS tools, such as Mentor Graphics® CHS and VeSys® 2.0, are designed from the start to be flexible and to provide robust standard functionality, plus the ability to adjust the tool’s automated behavior, reports, and graphical outputs.

Today’s leading COTS solutions span the process, fostering data re-use and consistent communication among users, projects, and sites. A relatively small number of distinguishing features makes a big difference in both operations and outcomes:

Flexible Graphic Formats
Because no industry standard exists for harness drawings, many harness suppliers must support multiple graphical formats. COTS tools can solve this challenge with user-configurable graphic output, plus the ability to dynamically change the display as the underlying design data changes. For example, flag notes can be automatically displayed where a connector is required to use gold-plated terminals. Among the issues summarized earlier, these graphic capabilities simplify exchange among proprietary tools and data re-use.

XML Data Portability
The XML language is a self-documenting format that enables different applications connected to talk to each other via the Internet. It is easy to understand and easy to transform (at low cost) into the format required by the target system. The latest COTS design tools use XML to convey both the data for the harness itself and its graphical image. 

Tunable Tools and Rules
Most modern design applications allow the processing behavior of the application to be “tuned” with rules. These rules may be configured to enforce particular end-customer constraints or apply the know-how of the supplying organization. For example, the rules might specify a reliability constraint, such as prohibiting splices containing more than six wires. Similarly, they may support safety or manufacturability constraints.

Moreover, many COTS tools incorporate design-rule checking functions that enforce proprietary harness fabrication methods, automatically ensuring that failure modes are excluded from the design.

Reusable Data
Being able to re-use design data automatically and extensively is a key objective that provides measurable process efficiency and quality benefits. New-generation design applications leverage web technologies such as service-oriented integration architecture (SOA) to simplify integration with the corporate IT ecosystem (PDM, MRP, etc.).

Configurable Change
The latest harness design tools provide sophisticated change management capabilities that allow users to configure the application to interpret design changes from diverse import sources. Design change policies vary by OEM customer and/or project, and can be very detailed.

Purpose-built reporting features enable users to easily understand the nature of each change, and protect unchanged data. Incoming design modifications can be effectively merged with the value-added harness engineering work from the preceding harness design revision without risk of data loss.

Figure 2 summarizes all of the features and capabilities just described, and maps each to a succinct list of the process requirements it affects most. In truth, virtually all of the capabilities have at least some impact on all of the process variables.

Many capabilities that seem novel today will be indispensable tomorrow. The market no longer offers the luxury of time for manual processes or porting data among isolated “islands of automation.” The latest generation of COTS tools resolves issues that have long plagued designers and planners in the harness industry. These solutions leverage advances in design automation, data communication/archiving/retrieval, and simulation to deliver the efficiencies necessary to ensure competitiveness in the years to come.

Mentor Graphics supplies electrical and wire harness design software. Companies such as CHN, Bobcat, Caterpillar, Terex, Sennebogen, Komatsu Forest, and McCormick Tractors, have all benefited from incorporating such dedicated tools into their design processes.