Elektronik Praxis: Material flow optimization in the Intelligent Factory

The ideal just-in-time production does not require any inventory at all – theoretically. In practice, however, it will never be possible to synchronize the flow of materials in an SMT factory from the factory floor to the shipment of the finished product so perfectly that no storage is needed.

The flow of materials will always be a ‘breathing’ system that leads to an almost linear, sequential process only when it reaches the machine. In between the various stages there is a storage and buffering system that ranges from the supplier to additional storage on the factory and shop floor levels to the component reels on the placement machines. If one of these buffers runs empty, one or more machines may stop working because they run out of material. Therefore, it is quite understandable that many SMT factories maintain extensive ‘emergency’ stocks on their shop floor. Unfortunately, they take up valuable production space and block the use of the material by other lines – problems that can be eliminated with consistently demand-based planning approach.
Finding the right balance between demand and inventory requires the integrative use of data of the type practiced by ASMPT, the technology and market leader in software and hardware solutions for electronics manufacturing, with its Intelligent Factory. It must meet the following requirements:
•    Seamless and scalable material flow optimization on the shop floor
•    Intralogistics based an actual consumption
•    Avoidance of line stops cause by material shortages
•    Reduction of material on the shop floor
•    Having the right materials in the right quantities at the right time in the right place (4R principle)

Planning with foresight
Optimization software for intralogistics must continuously analyze the demand for material on the line, but it must also look to the future.  This is the only way to avoid material overages or shortfalls, or having to retrieve and reinstall a component reel that was removed and returned to the warehouse only minutes before.
ASMPT’s WORKS Material Flow Optimizer meets these requirements. Based on freely definable time slices, the intelligent application continuously calculates the material consumption and controls line logistics according to the 4R principle. It compiles data on the planned and actual material consumption as well as the material supplies currently on the line to determine the demand – dynamically and continuously. Based on this information, the application generates material requests to the central and local storage sites along with time-controlled transportation orders.
The WORKS application for a smooth material flow also organizes and optimizes material buffering in the setup preparation area for multiple products and lines. It checks for each reel that was removed after the completion of a production job whether it will be needed again for another order – for example, within the next two days. With the help of a docking station and color-coded lights, the employees receive precise instructions which reels need to be returned to the warehouse and which should remain on the feeder in the setup preparation area. During the new setup, the application uses light signals to indicate which already set-up feeder should be mounted on which track of the feeder table. The WORKS Material Flow Optimizer and WORKS Production Planner applications from work together – true to the principle of data-based, intelligent manufacturing. Via an interface, production schedules can be transferred directly to the intralogistics plan. As a result, changes can be implemented much more quickly. Since the WORKS planning application imports the production orders directly from the ERP system, the chain from order receipt to on-time and situation-oriented production planning to material provision according to the 4R principle on the line is closed without leaving anything out.

Material management for the whole factory
In SMT production, material inventories are usually spread over several storage locations. The closer to the line a storage facility is located, the smaller the inventory and the shorter the access time. As a result, implementing the 4R principle involves a complex system. This is where Factory Material Manager and Factory Automation come into play. Developed by ASMPT’s software division and MES specialist Critical Manufacturing, factory-level applications keep track of material stocks across the entire factory and control autonomous transport systems (AMRs) from material receiving to order picking for the production to testing, packaging, and finished-goods shipping. The material spectrum includes blank and assembled circuit boards, components, tools such as stencils and squeegees for the printing process or nozzles for the placement process, as well as consumables such as solder pastes or cleaning agents.

Storage and transportation hardware
Today, modern intralogistics stand and fall with the integrative use of data by process, product and factory applications. But the hardware is just as important as the software, which is why highly scalable and cascadable automatic storage systems are a critical necessity. They must also be space-saving to keep their total footprint small. Finally, the intralogistics hardware is complemented by a fleet of autonomous transport vehicles.
This is where ASMPT puts its trust in system partner CTS, an innovative company that offers matching automatic storage systems for every production environment, making it possible to process additions to and removals from storage reliably and without human assists. Intralogistics systems from CTS fit perfectly into ASMPT’s Intelligent Factory concept while allowing ASMPT to remain true to its open automation principle because all applications for material flow optimization are designed to work with transport and storage hardware from other manufacturers.

The circuit board controls program changeovers
When it comes to optimizing processes, saving time and making employees’ work easier, program changeovers play a critical role. In most SMT factories, the respective line must first run empty before a new program can be run. This is often followed by time-consuming setup changeovers and the manual downloading of new programs and parameters onto the machines. In general, it is worthwhile to combine similar products on one line and set up the machines across the board. With such so-called family setups, manual interventions are no longer necessary, at least on the hardware side, when changing programs.
With hardware and software from ASMPT, program changeovers on SMT lines can now be executed automatically by passing the data of the respective circuit board from machine to machine via the standardized IPC-HERMES-9852 interface.
When substrates are unloaded from the magazine, the relevant data is transmitted to the DEK TQ solder paste printer via a barcode reader or directly from the production planning system. This data is subsequently reconciled with the values stored in the line control application. If a recipe change is required, the new production program is downloaded automatically. Once printed, the circuit board is passed along to the Process Lens system along with its IPC-HERMES-9852 data. The SPI system executes an internal data check and changes the program, if necessary. Next come the placement machines, which perform another Line Control reconciliation and download new programs if needed. Even the conveyors adapt automatically to the width of the circuit boards being transported. Thanks to this PCB-induced approach, the line no longer needs to run empty when a product change is required. And with a family setup, product changeovers can be executed with no operator involvement at all.
If a manual assist is needed, the system can automatically request a specialist from the smart operator pool thanks to its interface to ASMPT’s WORKS Command Center, the application for multi-line operator deployments.

Keeping an eye on the overall system and the ROI
The ability to have automatic program and product changeovers triggered by a printed circuit board as it moves from machine to machine shows how important the integrative use of data is in intelligent manufacturing today. “To successfully optimize your material flow, you must map almost the entire SMT manufacturing process with your hardware and software product portfolio,” explains Erwin Beck, Director Product Management Automation Solutions at ASMPT. “This is the only way to gain the necessary experience and the only way to accumulate the know-how needed to implement the 4R principle. That’s why ASMPT with its comprehensive portfolio is the market leader and the right solution partner, particularly for intralogistics optimization projects. Our goal is not to maximize automation, homogeneity and customer retention through proprietary systems, but to maximize the customer’s return on investment.