Light Metal Zinc
Zinc Alloy Parts in Foundries: How to Define Their Specifications?
Specifications are the constraints and requirements defined by a client's order on how to produce a specific product. In a simple and concise manner, it defines the functional requirements and performance values expected of a part. This information is essential to each of the foundry’s processes for the proper execution of the part and must be known before an order is executed.
1. General Data
First and foremost, the foundry must obtain general information from its customer on the part to be manufactured:
- Quantities: geographical and sectoral scope, volume
- The serviceable life of the part
- The material (in this case Zamak)
- The destination of delivery
- The required certification
2. Communication Process
In order to optimize exchanges between the foundry and the customer, several communication procedures should be put in place, including:
- The means of submission of the CFD files (Definition of the digital model = digital file of the part to be produced, including all the information necessary for its manufacture)
- The status of client CFDs
- The status of the CFDs required by the client, after modification/correction
- The CFD or paper file
- The time slot for communication
3. Development Process
This refers to a set of partially predefined steps that contribute to the controlled and successful manufacture of the part.
- Plans or a viable CFD
- The desired tolerances. At the very least, functional tolerances.
- The permitted areas on the part to install the injection and ejection points.
- An FMECA produced (Failure Mode, Effects and Criticality Analysis), to ensure that each customer requirement will be met
- The functions of the part
- Machining, assembly and surface treatment requirements
- The environment in which the part is used
- The specific characteristics of the part
- Associated documents
Technical specifications for casting and surface appearance must be defined. At this stage, it may be useful to compile a "checklist" with the foundry, in order to comprehend the specifications and the costs involved. On the website of the NADCA (North American Die Casting Association), you can download standard specifications for die casting, including these popular checklists to evaluate foundry specifications, product and surface processing.
4. Approval of Tools and Manufacturing Processes
The tool/product/process approval ensures that the product will be designed and manufactured according to the rules and requirements defined by the customer. In order to assess the expected performance, the following things are required:
- The initial samples and control specification
- An FMECA process, ensuring that each step of product modification complies with customer requirements
- A capability study ensuring that each product modification is statistically verified
- Control methods and means
- A "Limited Industrial Series” ensuring a repeatable and reliable process of serial orders.
5. Documentation Requirement
To ensure optimal quality management, the foundry uses a database that must be centralized and structured. This database includes:
- The duration for completing tests
- The required certification
- The requirements for traceability
- Other specific requirements
6. Logistical Requirements
Logistics play an important part in modern foundries. It is vertically integrated in all the processes of a die casting plant. In order to guarantee an efficient logistical process and to be able to deliver the right quantity on time and at the highest level of quality, foundries offer an adequate packaging and order preparation system:
- Packaging - quantity - bulk/storage
- Specific packaging (tray or other)
- Stacking height
- Safety stock
- Delivery date
- EDI (Electronic Data Interchange)
No specifications go without a provisional schedule that includes the main stages of production of the part. This schedule includes various deadlines:
- Review of plan and demand
- Customer validation of the CFD part fitted for die casting.
- Review of tooling concept (parting / splitting line)
- Order date of tooling design study
- Order date tooling production
- Date of submission 1st parts, results 1st test
- Date of submission of initial samples
- PPAP (Product Part Approval Process) submission date
- Date of first series production
Experience with Zamak shows that the foundry should be involved as soon as possible in the development of the project and the compilation of the specifications. The success of a zinc alloy casting part is a team effort and the result of collaboration. The foundry's design department puts all its know-how at the service of the client's design department in order to offer the best possible alternative part, both in functional and economic terms.
This article was first published by Experience Zamak.
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