Nadca 207–2022 – Categorization of die parts

If we have already designed the parts of the die, the next logical step is to categorize them in terms of process steps during the manufacturing of the die, as well as traceability during its use. It’s a logical step, but it’s not new at all.

Few people know that I started my career in 1979 as the head of the tool shop at Plastimat in Liberec, today one of the largest toolmakers in the CZ with a changed name to Magna Exteriors. Here I was in charge of the production of new tools as well as the storage and maintenance of existing tools. And even then, with the help of the Minsk 22 mainframe computer and Jarda Fryč, now a renowned librarian from Liberec, we tried similar procedures on plastic moulds.

So, what to imagine behind it? The answer can be found in the publication Nadca 402 – Product Specification Standards for Die Castings.

Fig. 1 – Determining the functionality of individual parts of the casting

Fig. 2 – Example of coding die parts according to Nadca 402

When designing the die, we split the individual surfaces of the casting in terms of functionality or cosmetic properties (Fig. No. 3), and the estimated or planned lifetime of the part (Fig. No. 4) are taken into account. The coding parameters are then introduced as a new field in the BOM list (Bill of Material), created for example in SolidWorks.

The categorization of the functionality of the individual surfaces of the resulting casting is an internal matter of each foundry (Fig. 4), but it should be defined in such a way that it is possible to set damage limits for the quality of the casting, repair of the insert or for its replacement. However, an equally important factor will be the permitted steps for maintaining or improving the properties of the insert, e.g. the possibility of applying the ABP method (stress annealing + sand blasting + shot peening), nitriding, oxidation or recoating with thin PVD layers.

Fig.  3 and  4 – Categorization of die parts according to Nadca, publication 402

The result of that activity is then introduced as a standard field in the BOM list of the die, e.g. in SolidWorks (Fig. 5)

Fig .5 – An example of a classic BOM list created in SolidWorks

Coding of die parts according to Nadca 402 is two-level: according to surface functionality and according to expected lifetime. Unfortunately, for reasons unknown to me, Nadca 402 does not take into account the existence of Nadca 207, where one more obligation is added, to specify die parts according to the type of material testing, i.e. Class 1 and Class 2. This categorization is at least as important as the previous category, because it clearly determines the process steel purchasing and testing workflow.

Fig. 6 – Categorization of Heat Treatment Quality

The classic BOM list of the die should then have this form according to Table 1. It contains all the necessary data for the purchase of steel and for its testing at the input, and will also serve as the basis for another table needed to monitor the die in operation in the foundry. However, data on the results of the testing will also be collected in this table, which we still have to hand over to the pressure foundry in the “Tool Book” of the die.

Tab. 1 – An example of a BOM table design for the production of a die casting die

The result of this approach to the bill of materials will be a form where categorization codes will be assigned to each part. Each combination will then have its own workflow, ensuring full traceability from the purchase of material, through input testing, machining, heat treatment, testing after quenching and delivery of the die. It is therefore a complete “Tool Book” of the die, which will then be followed by monitoring in the foundry.

Fig. 7 – Example of die parts categorization

The foundry will then follow up the BOM list designed in this way with additional information from production. In the “Tool book”, information is gradually added about the date of installation and date of removal of the die, the number of cast pieces, service interventions, the use of spare parts, the application of annealing to remove stress from thermal fatigue, costs, the degree of wear, and other data necessary for die parts  assessment forms.

Tab. 2 – Die Casting “Tool Book” Design Example

To evaluate individual types of defects and their extent, it is possible to create different defect maps, see example of classification of surface damage due to thermal fatigue from Uddeholm.

Fig. 8 – Surface classification map according to the number and density of cracks (Source Uddeholm)

February 15, 2023

Jiří Stanislav