Digitalising the planning of one of the toughest manufacturing processes Source: Aimtech
The production of exterior plastic components, where not only the injection moulds themselves need planning, but painting does as well, is one of the toughest production processes in the automotive industry, because it is so complex. Magna could write whole books about this: they make plastic components for passenger automobiles at their branches in the Czech Republic and through their subsidiary Decoma in Germany. You can find bumpers, rear hatches, radiator grilles, doorsills and more manufactured by Magna in cars from Škoda Auto, VW, BMW, TPCA, Jaguar, Daimler and even Audi. Every plant has its own specifics, and so no one unified system can be deployed at all branches without making some needed adjustments. Additionally, a large number of manufacturing operations and constraints must be taken into account. The solution? The Asprova advanced planning and scheduling system.
Magna Exteriors Bohemia’s requirements
Specifics of the manufacturing process at Magna Exteriors
Unified and correct data for everyone
Correct production planning is only possible when APS (Advanced Planning and Scheduling) works with the same data as neighbouring systems, and vice versa. So when deploying a planning system, it’s important to know when data will be available, and at what quality. It often happens that planners have different data available from systems at different times. Thanks to ERP, MES and APS integration, imprecision from individual sources is eliminated, improving the quality of production data. At the same time, the production planner always has the same data available at a given moment, making their work more precise. Once Asprova APS is deployed, there is only one system that is collecting the data needed for setting an optimal production plan.
Plastic injection moulding
The planning of multiple-cavity and family moulds The high-pressure plastic injection moulding process is primarily constrained by the availability of the moulding tool. Various types of moulds, from the simplest single-cavity moulds to multi-cavity moulds with an exchangeable core/insert or a sealable cavity, often make production planning more complicated than it would be otherwise. The individual items are paired or modified, with various plugs or tolerances. At Magna, Asprova APS was set up so as to take into account all of these constraints and, to some extent, to stand in for the planner and their experience. It simultaneously provides a calculation of the materials requirements for production – when calculating the size of production batches, it takes into account the combination of products in the moulds.
The process of setting an optimal production batch size The production hall must be able to react flexibly to new customer requirements and to other non-standard situations. Using the AutoReplenishment feature, Asprova APS can provide the recalculation of planned orders or the creation of new orders, and this based on changes that have occurred. The system factors all settings into its calculation, in the form of cumulations, cycles, warehouse stock levels and more. This enables it to set an optimum production batch size.
JIT/JIS assembly work centres
Differing requirements for JIT lines When a requirement changes by way of a call-off fluctuation, the supplier needs to react by changing the size of the production batches that affect the given assembly work centre, or by changing their ordering. For these purposes, the updating of the production plan and the fixing of the upcoming period is a part of a planner’s daily routine. Through this, an optimum batch size, dependent on the change to final needs or increase in reject rate at the final work centres, is achieved.
The speed of change re-planning on the JIS line One specific that can be found at most JIS assembly lines is an unchanging work queue that follows the sequence of requests from the OEM. But this kind of situation is complicated for planning, because one does need to react to changes in call-offs. One solution may be to increase warehouse stocks of materials and semi-finished goods directly at JIS work centres. However, this kind of increase is ineffective whenever there is a large array of final products, as there is at Magna Exteriors. Asprova APS enables planners to react in real time to changes or new requirements in sequence; the re-planning itself lasts roughly a few seconds. Also, through Asprova APS, Magna Exteriors has become able to pre-configure autonomous re-planning scenarios for routine interventions. This too has saved time for planners and made production and storage more efficient.
The production of exterior plastic components, where not only the injection moulds themselves need planning, but painting does as well, is one of the toughest production processes in the automotive industry
The exterior part paint shop
Painting-cycle planning Every part that needs painting is suspended within a skid (see below) that continually rides through the spray booths. The skid has varying capacities, and when there’s a change to individual positions’ distribution, its hooks (jigs) need to be physically moved or exchanged. Another constraint is the size of the segments (the same product types in a row) and the number of paint exchanges in the spray booth. APS reacts to such changes in two steps. In the first, it composes a design for the painting cycle itself and a distribution into individual jigs (based on customer orders out to a relatively long horizon). The first step additionally addresses any needs for Double Paint, pre-lacquering etc. The second step is the planning of the right paint in the right amount for the given variant.
Work with paints One other Asprova feature is the grouping of orders into painting units. The goal is to keep painting from commencing within a sequence if the given paint colour is not yet ready, and to simultaneously prepare a report for the paint exchangers. The painting robot only has a limited number of filling systems feeding it, and so paints need to be exchanged during its work. Exchanging the paint in all systems takes varying amounts of time, and can take up to several hours. Downtimes can then be unpleasantly long – if, that is, proper planning has not occurred and/or the staff in charge of paint exchange does not have the proper information.
Another stumbling block here lies in the plentiful process dependencies among the paint used, the chemicals and the painting process. In the case of painting with saturated colours along with bright ones, a constraint arises precisely due to the colour combinations used. Because of this, certain Prohibited Colour Combinations are defined.One real-world example is the colour sequence “pink then white”. If this sequence were to be used, the white paint would be affected by the colour pigment for the red paint, and thus painting in this sequence is not possible, because even after rinsing of all systems, one hundred percent quality for the white paint cannot be guaranteed.
For Double Paint, the same part is sent to the paint shop twice. In the first round, it is painted with a primer, and then it is placed in the work queue a second time, this time for final painting. Not all parts are painted twice, and the production plan must take this eventuality into account as well. The system precisely defines in what position (what jig) a part must be suspended after its first painting in order for it to be re-queued. It is therefore important that all work centres have access to reports that display the work queue clearly and simply. Production-hall foremen and the planners themselves each have their own outputs from the system. Asprova thus ensures that all work centres will be working with the same data and will have precise information for their activities.
You can find bumpers, rear hatches, radiator grilles, doorsills and more manufactured by Magna in cars from Škoda Auto, VW, BMW, TPCA, Jaguar, Daimler and even Audi
Synchronised work centres In situations where interim storage for semi-finished goods exists only between the injection moulding area and the paint shop – and does not exist between the paint shop and the assembly line – all processes need to be synchronised. For the demanding planning of the painting process, the question arises of how to plan individual batches so that the assembly line can be stocked with precisely the defined quantity, with the delay needed for processing of the overall batch.
The solution is taken into account much earlier, within the structure of the painting cycle, where Asprova APS chooses the segments that form the core part of the sequence of input batches for assembly. It intersperses other, lower-priority or non-assembled semi-finished goods between these core segments. By planning the paint shop in this way, it ensures a smooth flow of parts to the assembly line without the need for an interim storage space. This in turn reduces products’ lead time and the likelihood that quality problems caused by storage or increased handling will arise.
Reporting
Visual management Visualisation of the production plan is essential from the standpoint of Industry 4.0 and the digitalisation of the manufacturing chain. It enables the planner to double-check and verify the production plan more quickly and efficiently than they could via tables and verification reports. Asprova’s clear diagrams and graphs, which can be configured for multiple analysis, provide the planner with the unique advantage of not only being able to make decisions from the standpoint of the workshop plan for the next few hours, but also being able to quickly orient themselves within the long-term horizon and confirm frequently hard-to-predict situations with high precision.
SOLL/IST reporting Thanks to its clearly presented charts, Asprova offers a deep evaluation of the state of individual machines, tools, and workers. Every manufacturing operation is monitored in detail from the standpoint of materials consumption, final-product production, a work centre’s real-work performance and production releases. These characteristics make it possible to define a precise report comparing planned production operations with real production results. Similarly, the precision and performance of planning in relation to the average values that were expected in the production plan can be evaluated as well. With Asprova, one has access to a perfect tool for the evaluation both of manufacturing/logistics and of the actual precision and efficiency of production planning.
Digital project delivery
Standardisation and transferability of know-how to the customer Asprova APS is a system that is broadly supported by new technologies. Video documentation is freely available via a dedicated YouTube channel. Asprova is furthermore supplemented with countless training materials and templates for production planning models, on whose basis a planner can simulate new situations or planning strategies before deployment into their own production planning model. These documents enable planners to achieve complete independence after the initial implementation.
Benefits
The Skid (or also SkidType, ST) is a metal construction that bears hooks (“jigs”), onto which painted parts are suspended. Varying numbers of parts can be suspended on one skid, depending on their size (e.g. 1 bumper vs. 1,000 caps). Painting Train (PTT) – a table with the distribution of the individual SkidTypes. Colour System (CS) – the filling of the painting robots with paint. Double Paint (DP) – two-round painting, first with a Primer and then with the overlying paint.
Source: Aimtec
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