There are many similarities between Backlighting Production Design and Small Volume Design. Production design and small volume design both have their limitations. Without a clear understanding of their strengths and weaknesses, it can lead to many problems including delayed lead times and non-desirable parts produced. An early consideration of HMI Backlighting design may help streamline the design process
Issues and limitations for not understanding Production Design vs Small Volume Design
-Longer turnarounds (lead times)
-Lack of desired fit/form/function
Lead times/turnarounds are quite different from Large Production Volume Design and Small Volume Design for prototypes, low volume quantities, etc.
Small Volume Design has a shorter design lead time. This is because it requires minimum tooling, minimum process design and minimum fixture design. Small Volume Design for HMI backlights typically requires a “one-at-a-time” assembly (“Single-Up” assembly) approach, whereas Production Volume Design requires more in-depth design regarding tooling, process design and fixtures. The Production Volume Design takes much longer because more resources, design time and planning are needed. Production Volume Design has a “Many-at-a-time” assembly (“Multi-Up”) approach. This means that small volume parts can be produced sooner, but at a slower throughput, while Production Volume Design produces parts later at a faster throughput.
Small Volume Design requires minimum resources up front. This allows for inexpensive proof of concepts, low cost tooling, and fast prototypes of low quantity volumes produced. With the Single-up assembly process it has a slower throughput but allows for an excellent option for proof-of-concept validation with lower up-front expense. The lead times for these items typically range anywhere from 3 to 6 weeks. Production Level Design requires additional resources up front. This may cost more at first via production tooling, production fixturing, custom packaging, and custom dies. The lead times for these items typically range anywhere from 8 to 12 weeks. Once the Production Design is finalized, the cost efficiency is optimized, and throughput is high. If there is a high degree of design confidence and low risk assessment one option to reduce overall production launch cost is go straight to Multi-Up production. How Do I cost Reduce My Backlighting?.
A significant difference between Backlighting Production Design and Small Volume Design is the assembly. With Production Design keep in mind production efficiency throughput with methods such as heat stake, adhesive or even mechanical bonding processes allowing for large quantities to be produced simultaneously. Additional methods include edge registration (Multi-Up and Single-Up), pin hole registration, or even edge registration and pin hole registration in the housing/fascia itself.
Desired Look/Function & Non-manufacturability
Trying to produce large quantities of a product using Small Volume Design will not work well. This could result in breaking manufacturing tolerances with a non-desired look/function. Small Volume Design is manufacturable on small scale. If an application requires 200 assemblies per year, there is no reason to pay higher investment costs for production tooling but rather do a single-up assembly approach or a Small Volume Design. This will help streamline a desired look and functionality, therefore, understanding the intended product volumes early on is key to preparing a plan of action to achieve the best results on your specific application requirements.
When designing for Production Volume or Small Volume, keep in mind manufacturing tolerance stack-up when selecting production methods. Too tight of a tolerance and parts may break during build, too loose and there is too large of production variability. Low Volume design does not require the same tolerance since throughput is built one at a time and by hand. High volume scrap rates are consequential for cost and capacity, for production volume, the efficiency rate of manufacturing is much higher and there is a higher liability.
Planning and understanding an application’s needs can help determine what kind of production design is needed for your HMI backlight application and when to utilize the various manufacturing options available to optimize your desired results for cost, timing, quality, and performance.