Whether you work in hardware manufacturing or software development, a company’s production cycle is an indicator of its ability to convert assets, inventory, and supply chains into cash flow and profits. In the hardware space, the actual act of fabricating and assembling a widget is just one aspect of the overall production cycle. There are other factors to consider in running a factory and managing production.
Manufacturers that can control their cycle time and ultimately reduce it can see some major benefits that accumulate over time. Cycle time reduction benefits include faster time-to-market and, if other cost factors are kept in check, an opportunity for higher profitability. Cycle time reduction also helps a company be more competitive against other businesses that offer similar products to the same customer base. Therefore, companies that develop and manufacture electronics products need to reduce development and production times to meet changing customer demands.
Proper factory management and analysis is critical for realizing cycle time reduction benefits.
Analyzing Cycle Time: Little’s Law
Physicists seem to have their hand in everything, including developing mathematical models for managing manufacturing processes. These management models are one of many factors that have contributed to cycle time reduction in a variety of industries. Going into the future, creative factory management and new fabrication methods, like lights-out manufacturing and a broader use of additive manufacturing in R&D, will help continuously improve factory productivity in a range of industries.
Cycle time (CT) is the average amount of time a unit takes to move through the manufacturing process. CT is related to the start rate (SR) for a fabrication run and the number of units being processed at any given time (called work in progress, or WIP) by Little’s law:
WIP = (CT) x (SR)
The fact that WIP and CT are directly proportional means that reducing the number of lots being processed at any moment (i.e., reducing WIP) will reduce the CT value for the process, assuming SR is constant. Likewise, for a fixed WIP value, increasing SR requires decreasing CT.
What does this mean for your manufacturing process? Let’s look at an example:
- Suppose your goal is to produce 1,000 units per day with your manufacturing process.
- This means that your process needs to produce about two units per minute.
- CT is the inverse of this number, or about 30 seconds per unit.
- If this process requires a start rate of, say, 5 units per second, then you will have 150 units moving through the process at any given time.
There are a number of ways to analyze Little’s law:
- Keeping CT low for a given SR value allows you to reduce WIP, ultimately increasing your output and reducing lost yield if there is a sudden problem with the manufacturing process.
- If your CT value is high (i.e., the process takes a long time), you can increase daily output by running multiple process lines in parallel without significantly increasing your risk of yield problems.
- Finally, for a given CT value, you can decrease WIP (and thus yield) by using less than your total capacity, i.e. by reducing SR for the process. This gives you room to expand production capacity without investing in new manufacturing assets.
These different management choices will affect your throughput, risk, and costs.
Cycle Time Reduction Benefits Beyond Manufacturing
Controlling and reducing cycle time creates real economic benefits for large and small companies, particularly in the integrated circuit and PCB industries. If your company is the first manufacturer to provide rapid prototypes or product samples to a prospective customer, you can get to market and win sales before a competitor. This can make or break smaller companies.
Similarly, longer cycle times can cause a huge amount of WIP to remain in the production pipeline when the market enters a downturn, and prospective customers may move on to a company with the faster time to market.
The other cycle time reduction benefits include:
- Shorter cycles of learning (COL), ultimately leading to a shorter development time during R&D.
- Rapid prototypes that can be produced and tested at a faster rate, hastening design-build-test iterations and making the manufacturing process itself quicker.
- The ability to ramp up manufacturing yield at a faster rate once a new product is transferred to production.
Reducing cycle time can aid logistics planning and decrease time to market.
Taking Control of PCB Cycle Time with Additive Manufacturing
Using an additive manufacturing system for PCBs can help you take control of your cycle time and decrease it for a variety of products. An additive manufacturing system uses a layer-by-layer printing process to fabricate a product, and the cycle time involved in this process does not change with device complexity.
Using an inkjet system that prints conductive nanoparticle inks and a dielectric substrate simultaneously allows you to additively manufacture a finished PCB with a fixed cycle time. This characteristic of additive manufacturing processes makes WIP highly predictable by offering a fixed cycle time for any PCB you want to produce. It is important to keep in mind that the speed of the printing process is key to the volume that can be produced in a given time period.
This characteristic, where cycle time is independent of device complexity, arises because the layer-by-layer printing process does not need to be modified for more complex boards. Contrast this with traditional subtractive processes, where more complex boards, such as multilayer PCBs, require more fabrication and assembly steps as the number of layers increases as well as result in a lot of waste. This is not the case with additive manufacturing processes for electronics.
Because the cycle time is constant for nearly any level of complexity, the cost per unit is also nearly independent of device complexity. The elimination of redundant plating, etching, pressing, and drilling steps offers a lower cycle time compared to traditional subtractive processes, particularly for multilayer PCBs.
This ability to fabricate boards with any level of complexity using a single process could make an additive manufacturing system ideal for low-volume manufacturing runs of highly complex PCBs. Nearly any interconnect architecture can be printed with this type of system, and these systems allow direct 3D printing of non-planar PCBs with embedded conductive components. Assembly time can also be reduced if multiple parts are redesigned to be produced in a single print process.
This ultimately frees designers from the constraints imposed by subtractive processes. Also, additively manufactured PCBs can include intricate details at no added costs. In addition, additively manufacturing your electronics in-house eliminates the need to rely on an external provider with a long purchase-order process. All of this can be done with a fixed processing time, allowing you to take greater control over your cycle time and costs.
You can realize cycle time reduction benefits and increase productivity in your PCB manufacturing processes when you work with an additive manufacturing system that is specially designed for fabricating complex 3D-printed electronics. The DragonFly LDM is a perfect system for fabricating planar and non-planar electronics with any level of complexity. You’ll be able to stay competitive and produce novel devices with lower costs and faster cycle times. Read a case study or contact us today to learn more about the DragonFly LDM.