7 tips when considering standard vs. custom motion solutions

Features - Motion Control

Defining a motion system that fulfills technical requirements and fits a project’s budget can challenge even the most experienced motion control equipment buyers. Aerotech’s Brian Fink offers tips about the suitability of standard and custom solutions to ease this challenge early in the process.

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July 13, 2017
Brian M. Fink
The PlanarDL, a two-axis XY mechanical-bearing direct-drive stage, is an example of a standard configured-to-order product.

Success for many advanced manufacturing and inspection- related projects in aerospace often hinges on high-precision motion control. Comprised of mechanical positioning stages and control electronics, the motion solution represents the platform upon which the entire process is based. Many buyers can easily appreciate the convenience of conforming to a standard solution, however it is often worthwhile to consider customized solutions at an early stage.

The decision of standard vs. custom is far from black and white. There are varying degrees to which products and solutions can be defined as standard or custom, and a key element to a project’s success is to gain a better understanding of this continuum and the tradeoffs to be made in the selection process – what is most ideal for the project at hand.

The following factors are a starting point for buying teams tasked with securing a precision motion solution.

1. Standard motion solutions

This elevation-over-azimuth gimbal is an example of a custom assembly using standard ALAR direct-drive rotary stages, customized mounting and interface components, and precision alignments.

Standard motion solutions consist of catalog-level products such as linear and rotary positioning stages, motors, and controllers already designed and documented, with proven performance characteristics typically detailed in specification tables.

There are three levels of standard motion positioning solutions:

  • Standard, off-the-shelf – Motors, control electronics, pre-configured positioning stages are manufactured and qualified in advance by the supplier and typically ship directly from the supplier’s inventory with quick delivery.
  • Standard, configured-to-order – Users can tailor the solution while still using on-hand inventory by selecting configurable parameters, such as travel length, motor, feedback options, or amplifier current and bus voltage. The supplier then builds the product to the client’s required configuration using stocked components (see photo on page 16), providing clients with flexible options while still offering reasonably fast delivery.
  • Standard, manufactured-to-order solutions – This offers the advantages of a standard product, including catalog performance specifications and documentation, however this does not necessarily mean in-stock. Lead times are longer and may be prone to variability throughout time.

2. Custom motion solutions

There are different degrees to which a motion positioning system can be customized. A supplier of custom motion control equipment uses its engineering and manufacturing resources to translate the buyer’s needs into a tailored, specially-documented solution designed to meet requirements. Custom motion positioning solutions can be categorized as:

  • Custom assembly of standard products (see photo on page 18) uses the supplier’s standard, core building blocks to generate a unique design to fit the client’s requirements. This typically involves special assembly considerations such as cable management, mounting brackets, precision alignments, and possibly global workpoint or machine specifications. While a few custom components may need to be manufactured, the supplier may already have several of the standard components on-hand, often resulting in faster delivery.
  • Customization by modification of standard products – A reasonable approach when a standard product does not entirely meet the needs. An application may require altering an otherwise standard stage to have a special travel length and a specific mounting hole pattern or surface treatment. Although the motion solution is based around standard products, it is important to recognize that it is genuinely a custom solution in that it requires dedicated engineering support, special manufacturing considerations, and documentation (see photo on page 20).
  • Completely custom, ground-up solutions – Sometimes necessary to meet a uniquely specific and detailed set of customer requirements that cannot be achieved by customizing standard solutions. Although more resource-intensive, completely custom solutions need the least amount of technical compromises and are often associated with the lowest total-cost-of-ownership throughout time. The photo on page 22 depicts a completely custom vacuum-compatible solution.

3. Total motion solution budget

This dual direct-drive rotary motion platform uses modified Aerotech rotary motion simulators (ARMS) rate tables and standard control electronics as part of a custom-designed and integrated sensor testing platform.

Prior to engaging suppliers, a buying team should have a drafted statement of the work, providing a technical description of the initial requirements and a budgetary price range.

Initially, standard motion solutions may seem to be more affordable than highly-customized solutions; however, it is possible that the buyer’s engineering and production teams may incur added costs associated with design, manufacture, and integration work needed to close gaps between their requirements and the seller’s supply. In the case of original equipment manufacturer (OEM) projects, high volumes can amplify these additional costs so OEMs and higher-volume end-users may benefit from considering a custom solution, which may involve one-time charges to cover costs associated with engineering services, special tooling, and fixturing. Although this could contribute to an initially higher cost, it can reduce technical and financial risks to buying organizations otherwise unable or unwilling to assume these responsibilities. For high-volume motion systems, one-time costs are usually insignificant throughout the project’s lifespan.

4. Delivery time requirements

Standard off-the-shelf items can typically be received within days of order placement, while standard configured-to-order items will often take days to a few weeks, due to the need to assemble components and subsystems into a final product. Standard products that must be manufactured to order exhibit higher variability in the delivery time, which depends on factors such as the availability of raw materials and components, as well as the supplier’s current production capacity and backlog.

Likewise, custom does not always dictate a long lead time. Custom systems that are assembled from standard catalog products, or even slightly modified standard products, may offer delivery times closer to the products that comprise their core components. However, it is important to consider that custom solutions will always incur some engineering design period prior to manufacturing, ranging from hours to months.

5. Meeting application requirements

In this example of a fully-custom two-axis XY direct-drive stage, every detail has been meticulously engineered for compatibility in a client’s ultra-high vacuum (UHV) environment, from the UHV-compatible cabling and specially-designed linear motors, to the lubrication applied to the bearings.

The decision to use standard or custom motion equipment depends on how closely the technical application requirements can be defined to fit a standard solution in comparison to how well a custom solution can be tailored to suit the application. And a buyer must differentiate needs from wants.

In many circumstances, custom solutions can more effectively meet a greater percentage of the application’s demands than standard solutions – customized equipment may be necessary to achieve stringent accuracy and repeatability specifications, geometric or dynamic motion performance requirements, or operational compatibility in ultra-high vacuum or cleanroom environments.

Conversely, a buyer might consider designing the application or process around a standard solution. That can be a wise approach for a variety of applications, but it may over-constrain complicated projects. An experienced supplier will be able to assist the buyer with defining the solution’s capabilities and statement of work, considering the tradeoffs between standard and custom offerings in relation to the application’s needs.

6. Internal expertise

Larger organizations with fully-staffed engineering and production departments may be better positioned to perform precision integration and customization work, and may be more willing to consider purchasing standard motion solutions – customizing and integrating them as needed to meet application requirements. On the other hand, these organizations often have engineering and production staff that are already occupied. Additionally, a buyer who independently undertakes a more sizeable scope of work also assumes greater risks. Customized solutions can certainly have an attractive convenience to larger organizations, while smaller organizations with more limited resources can also benefit from purchasing customized motion solutions.

Even if the buying organization can perform higher levels of integration in-house, smaller organizations may find it challenging to service and provide global support for extensively customized equipment. This risk can be mitigated by working with an experienced motion control partner who will provide the global pre- and post-sale support with an integrated or turnkey motion solution. Further, a custom solution’s total ownership cost can be attractive when considering soft costs associated with extended statements of work including engineering services, project management, technical support, and maintenance.

7. Use ease, life cycle

In the one-off use case, buyers may be sourcing motion equipment for in-house use such as for research and development (R&D), a production machine, or a one-time build of an integrated system for an end-customer. Here, standard motion solutions are a perfectly reasonable consideration, assuming technical and commercial expectations are satisfied.

Custom motion solutions offer benefits when many similar or identical systems are needed throughout an extended period. In addition to the advantage of obtaining a solution that is purposefully designed to achieve key technical requirements, custom solutions also give the buyer a higher degree of change control. Unlike standard motion products for which suppliers assume full responsibility for managing product lifecycles, custom motion solutions offer an open, collaborative process between the buyer and the supplier, giving the buyer a share in controlling product lifecycle and change management. This can be particularly appealing to OEM and other higher- volume buyers.

Conclusion

Although this is not an exhaustive list, these factors will help buying teams focus their efforts around finding motion positioning solutions that closely fit their needs. A successful buying team will engage motion suppliers early and communicate with them often. It is important to gravitate towards suppliers that offer technology and expertise, have a thorough understanding of the client’s application and requirements, and demonstrate a commitment to global pre- and post-sale support. A skilled motion control supplier will openly discuss the tradeoffs of standard and custom solutions, as well as the decisions to be made in relation to the client’s project. Ultimately, success is derived from the collaboration of both the buyer and the supplier.

Aerotech Inc.

www.aerotech.com

About the author: By Brian M. Fink, is product manager and Aerotech Inc. and can be reached at bfink@aerotech.com.