A, wire harness industry production planning scheduling difficulties
(1) product categories and standards, production planning is difficult to coordinate
Wire harness industry production, although the raw material is not much, but the wire harness products are up to tens of thousands of species. General harness companies, although not every month to produce tens of thousands of products, but the monthly production of more than 300 kinds of product varieties, and every month in the non-stop changes. At the same time, as companies to adapt to changes in the market, you need to adjust the production standards according to market requirements, resulting in the same specifications of the product, there are often several standards. The above characteristics, to the wire harness industry production plan management has brought trouble, objectively aggravated the complexity of enterprise program management, but also to the enterprise cost management has caused considerable difficulties.
(2) the diversity of customer demand, production orders change frequently
Customer requirements are diverse, and there is a great deal of variability, such as delivery, process production requirements, resulting in the result is that the production order process version and delivery must be accompanied by the corresponding changes to the production management has caused considerable difficulty. The existence of the problem, resulting in information systems, must be adapted to the changes in production orders, and to provide the sales order change information to the production sector of the transmission method.
(3) the increasingly complex production methods, collaboration is still not strong
Wire harness industry production, the typical single production, but the same model, different production orders, but to go through different production workshops, each other need to divide and conquer. The product is not type and structure of the frequent changes, will inevitably cause difficulties to the production. At the same time, combined with the special nature of the production of wire harnesses, coupled with the collaboration is not strong, resulting in each other can not be effectively articulated, thus causing considerable difficulties in production management.
(4) shorter production cycle requirements
Time is money, the market competition is becoming increasingly fierce, forced by the pressure of the market in its industry, the customer on the quality of wire harness products and the delivery of more and more demanding. At the same time, due to the wiring harness production process is determined, many wiring harness manufacturers have a relatively long production cycle. How to shorten the delivery time, become China's wiring harness industry have to think about the problem.
Two, an enterprise production planning scheduling APS case
A wire harness enterprise, there are more than 30,000 kinds of materials, each of which has a different downstream process; each harness needs to be corresponding to the finished product of a wide range of materials and different. In addition, the product will be constantly upgraded and customer demand changes, the material downstream process changes, resulting in changes in the process path, BOM structure, etc., to bring difficulties to the workshop production, production scheduling work is very difficult.
Prior to the introduction of the EPPU APS system, the company realized order scheduling manually by combining a simple APS software, and balanced the equipments according to the number of orders; it was not possible to accurately reach the multiple material levels involved in the orders, i.e., it was not possible to take into account the differences in process specifications of different line cards. As a result, when doing the planning, there is often a waste of raw materials caused by the first short and then long down the line, frequent switching of molds due to the difference in specifications of different line cards, inaccurate planning due to the inability to accurately calculate the man-hours between processes, and so on, resulting in a serious waste of production capacity and production efficiency.
Aiming at the current situation of the plan, the enterprise decided to introduce APS advanced scheduling system to realize lean production. The wire harness process route is basically fixed to determine the scheduling of the key processes: "off the wire - crimping - punching - pre-assembly - assembly". The scheduling rules for each process are different, and each production equipment for each process can produce different types of materials and production capacity. Specific needs are as follows:
(1) wire down process:
Wire down process is the first process of the wire harness, the process will be ordered by the finished product of the raw materials required to enter, according to the material process breaks down out of the final composition of the finished product of a variety of small wire (i.e., the raw materials for subsequent processes). The type of wire that can be produced by each downcomer depends on the specifications of the raw material.
Wire down process scheduling factors to consider:
Reduce mold switching time: special types of wires such as shielded wire or jacket need different molds, the same shielded wire row together; the same order under the same wire row in a device to produce, reduce the time to change the mold
The same specifications of the continuous production: such as the same shielded wire order number of the wire can be row together to produce, reduce the late search for the necessary information. The wires can be produced together to reduce the time needed to find the required shielding wires at a later stage
Considering the length of the wires: long wires are placed first and then short wires to reduce material loss
Dynamic man-hours: the wires are categorized according to the length of the wires, the number of orders and whether they are in the middle of the openings and other attributes, and each categorization corresponds to a different way of calculating the man-hours
Equipment processing equilibrium: the equilibrium of the equipment processing has to be considered. Ensure that all the work under the same order on different equipment production can end at the same time, quickly switch to the next process, the shortest transit time
Resource Priority: Prioritize the production in the automatic line machine
To the raw materials that make up the order for the work order: the line is broken down according to the process of ordering a variety of small lines required to small lines for scheduling, to facilitate the management and control of raw materials.
(2) crimping - carding process:
Crimping that is crimping terminals and other plug-ins, crimping equipment have fixed specifications, crimping different types of wire (according to the type of terminal classification). Punching process that the different wires together, the same terminal type is placed together for punching.
Order as a work order: crimping and punching process of the manufacturing cycle is very short (1S to 2S), so directly to the order as a work order scheduling, not directly scheduling the crimping and punching time of each wire, otherwise the plan can not be implemented.
Dynamic man-hours: Calculate the passing time according to the quantity of the order as well as the various types of small wires needed for the order
Switching method: The cycle time for crimping and punching is longer for some wires (e.g., shielded wires), so the switching process starts to do the crimping after the downstream process is completed by 1/3 of the quantity; and the switching process starts to do the punching after the crimping is completed by 1/3 of the quantity.
(3) Pre-loading process:
Pre-loading indicates that after the line type punching of an order is completed, all the lines of the order will be pre-assembled and matched according to the process set line, and there is a buffer pool before the pre-loading and assembling, and the pre-assembling and assembling will carry out the material handover through the buffer pool.
Load balancing: There are multiple pre-assembly shifts, and scheduling tries to ensure load balancing between shifts.
Transferring sequence: the pre-assembly process starts only after all line types of an order have clocked in
(4) Assembly process:
Assembly means that after the semi-finished materials are completed, the semi-finished products are assembled according to the drawings and the finished materials are output. Sub-product types to different shifts assembly (finished products), due to the limitations of personnel skills and number of people, assembly is a bottleneck process. Scheduling needs to consider the following factors:
Reduce switching time: In order to meet the delivery time, a single assembly team (station) as far as possible to assign the same material type of order tasks, in order to reduce the switching time.
Resource selection: the number of orders produced and the number of line card sheets within a certain range, and there is a sub-assembly diagram of the material, production in the assembly line production team production, other orders assigned to the assembly team to consider task balancing.
Three, APS solutions
1. Overall scheduling process and design
2. System modeling and scheduling results
Wire harnesses as a whole, although the process route is fixed, but the material is more material, and the material structure is complex, the constraints of the various processes as well as the rules of the complexity and is not the same, in order to reduce the amount of work to maintain the data, EPS APS using the processing process and process capability modeling. and process capability modeling.
(1) down the line process: down the line process to get the MES according to the order composed of material decomposition of the wire harness work order for the work of scheduling. Scheduling needs to be considered to match the factors, such as: wire material number, terminal material number, shielded wire order number / serial number, wire length and other attributes stored in the specification and reserved fields in the EPS APS system.
Specification matching: According to the different wire diameter, and special types of wire, such as shielded wire or sheath, requires different abrasives, therefore, will be down to the wire machine for the wire for resource specification matching settings, in order to reduce the time to change the mold, increase production efficiency. As you can see in the figure below, the lower wire machine 1 can be under 4 kinds of wires.
As you can see in the figure above, there are 4 types of wires that can be placed on the wire down machine 1
Dynamic man-hours: Based on the length of the wires, the number of orders, and whether or not there is a center opening, etc., the wire down machine will be categorized, and man-hours will be dynamically calculated by setting up a dynamic calculation of man-hours in the APS process capability of EPPU.
Translated into the system's manufacturing man-hours according to the rules:
Scheduling strategy: set up separate assignment rules for the downstream process, set up the assignment rules and resource evaluation expressions for the downstream line in the EPS system, to ensure that: the same order is scheduled to be produced together, with the same shielding line together, with the same wire materials are produced together, the long line is placed first and then the short line is placed later, and priority is given to using the automatic machine in the case of other equipment processing balanced.
(2) crimping-punching-pre-assembly process: crimping and punching process will be MES in the work order all combined into one job, in order to simulate the realization of the order in the crimping process under the scheduling of production.
Process Capability: Based on the number of sets ordered and the number of line cards categorized, the processing hours for the order in the process are dynamically calculated.
Wizard-type semi-automatic scheduling: Since the rules for transferring different types of products to a process are different and uncertain for the same process, it is not possible to uniformly set the transfer rules for the process. Therefore, using the wizard type scheduling function of APS, for crimping, punching, and pre-assembly process scheduling, using the SQL tool that comes with the system to flexibly define the relationship between the front and rear processes of the transfer order, and based on the front process to set the start time of the work scheduling of crimping, punching, and pre-assembly processes, semi-automatic scheduling is carried out to satisfy the business needs.
(3) Assembly process: assembly is divided into assembly line and non-assembly line, and adopts the production mode of single-piece flow. The labor hours of assembly according to the number of orders and line type of difference is not the same as the maintenance of the processing process.
Automated scheduling: In EPPU APS system, for the work of assembly process, set up the assignment rules and resource selection strategy, carry out scheduling to ensure that to meet the delivery date, the same material orders as far as possible scheduled together, and then carry out the task balance of the shift.
Wizard-type semi-automatic scheduling: on the basis of automated scheduling, the use of wizard-type semi-automatic scheduling according to the system calculates the day's production capacity and the load of the team to assist in manual decision-making on the results of the scheduling adjustment.
3. Workshop-level implementation promotion and expansion
The APS project team was composed of EPS technology implementation consultants and internal staff of the enterprise. Under the leadership of the EPS implementation consultants, the first workshop system implementation was accomplished through overall planning, step-by-step implementation, and gradual progression, in accordance with the EPS APS system's mature project implementation methodology, and project management experience, to enhance the understanding and support of the enterprise for the APS technology. The first workshop was completed in a step-by-step manner to strengthen the understanding and support of the enterprise for APS technology.
Through the first phase, an implementation team capable of identifying and solving problems is cultivated within the enterprise, and the enterprise's ability to apply the system is continuously improved. Combined with the flexibility and configurability characteristics of the EPS APS system, the various expressions and parameters modeled in the first workshop system can be simply and flexibly configured without the need for re-development or code writing. In the second phase, the in-house consultants and the APS team, rapidly replicating the experience of the first workshop, will take the lead in the implementation of the subsequent projects of the dozen or so workshops.
Four, the application of the effect
1. Through the implementation of advanced planning and scheduling system of EPS, and ERP/MES system integration, taking into account the production of materials, specifications, processes, and so on, a variety of constraints and rules, to achieve automated access to information on the order and work order scheduling, greatly reducing the planner's development of the plan the time needed to plan and planner's skills and experience requirements.
2. Considering the same wire type, material and other constraints on continuous production, equipment capacity balancing, reduce switching time, so that the production plan is more reasonable, improve equipment utilization, reduce capacity loss.
3. Scheduling granularity fine to the raw materials and wire card, considering the length of the wire, making the control of raw materials more transparent, reducing the loss of raw materials.
4. Through the combination of automated scheduling and semi-automated scheduling, it realizes the linkage scheduling between workshops and processes, and considers the flexible transfer sequence offset between processes, which reduces the intermediate WIP inventory and dull materials, and shortens the overall manufacturing cycle.
5. In response to changes in orders and production requirements and abnormalities such as order insertion, automated adjustments to the plan can be made quickly to enhance customer service capabilities.
6. The maturity and stability of the EPS APS product ensures that after the successful implementation of the first phase of the EPS-led enterprise-side assistance, the enterprise's own implementation of the promotion of the back of a few workshops to reduce the cost of implementation and increase efficiency.
7. The flexibility and configurability of Epto APS products ensures that the system continuously adapts to the development of business and product process upgrades, and the enterprise itself can realize the upgrading of the system model and applications in response to changes in the business, which reduces the investment in information technology for the future enterprise.