Die Casting

Modernizing Die Casting with Real-Time SPC

If there is an unsung hero in manufacturing, it may be die casting. Die casting is responsible for structural components in an astonishing number of products, such as: cars, mobile phones, golf clubs, prescription glasses, and coffee makers. And those components are more durable, more dimensionally stable, stronger, and lighter than they would be using most other manufacturing techniques.

But, like other industries, die casting has changed. And many die casting foundries are now facing the need to modernize. This need is challenging. It can mean finding new ways to capture data, control processes, drive continuous improvement, and meet customer demands for reports that substantiate a commitment to consistent Quality.

Capturing Data

Data is critical to Quality improvement efforts that a foundry may engage in. Trying to capture data on paper or in Excel, or even in older quality software, is no longer sufficient. These practices are time-consuming, prone to errors, and don’t leave the data accessible enough to use. They also can’t keep up. Die casting is a high-volume, precision operation. Hundreds of process and product measurements—some with unnervingly tight tolerances—need to be captured to modernize and manage it. That’s the reason for all the control systems and metrology devices integrated into a die casting cell.

A modern data capturing system should be automated, meaning it should capture data directly from measuring equipment and data sources such as: CMMs, PLCs, inline measurement systems, digital gages, vision systems, and more. WinSPC can process hundreds of measurements per second— exceeding all data demands of high-speed die casting cells, whether they are measuring product or process parameters, or both.

Real-Time Control

One of the primary reasons to capture data is to control a die-casting operation in real-time, to keep it humming along, consistently producing castings at specified levels. Unfortunately, many die casting operations aren’t set up with the real-time SPC alarms needed to do this. Without exact alarms, there’s no good way to know when a key characteristic is deviating from its target, when excess variation is present in a process, when trends in the data indicate that corrective action is needed, or even, when a casting part has passed all of its checks and can be advanced to the next process. Engineers and die casting machine operators will struggle to detect these scenarios, unaided. The data volumes are too high, and complexities are extensive.

The role of SPC (statistical process control) is worth emphasizing here. Real-time control is an SPC concept. SPC is a science, a proven science in which every measured value is evaluated against trend rules and variability limits to identify when assignable cause variation is present, and when an adjustment is needed before out-of-specification parts are made.

WinSPC supports all of the standard SPC rules. Additionally, it allows users to create their own rules to monitor for unique patterns or behaviors in their process. As violations are detected, users may be notified with on-screen visual updates, prompts for notes, audible sirens, e-mail notifications, or color-coded alerts on plant-wide dashboards. WinSPC can also be setup so that a violation programmatically adjusts an input setting, routes bad castings to a containment area, or, in extreme circumstances, shuts down the die casting machine. With WinSPC, there is no pressure on personnel to review every reading or every chart. The system, on its own, evaluates alerts and highlights worst-case situations for Quality teams to view at a glance. It is WInSPC’s real-time SPC alarms that make smart foundries a possibility.

Continuous Improvement

A common starting point when looking to improve a die casting process is to apply SPC to specific product measurements and process parameters. Foundries that don’t have a modern data capturing system, therefore, are immediately handcuffed regarding process improvement. Real process improvement opportunities don’t stand and announce themselves. They have to be mined for, from volumes and volumes of data, using the entire arsenal of SPC metrics.

WinSPC’s data capturing capacity ensures that the right data is available, and its built-in search and analysis functions highlight where problems have occurred that may be going unnoticed. Consider for a moment how finely a foundry could be tuned if, through SPC, an engineer could do the following:

  • Determine the extent to which each process parameter affects each critical measurement in a die casting machine’s castings
  • Establish the statistical capability of each die casting machine in the foundry
  • Assign jobs to specific die casting machines based on the job’s required tolerances and the machine’s capability
  • Define performance benchmarks for each die casting machine
  • Create real-time alarms based on SPC rules, such as control limits, that are tailored to each die casting machine and each job run on that machine
  • Filter data by job, die casting machine, control test violation, Cpk, and dozens of other options
  • Search for data that matches loosely defined criteria or narrowly defined criteria
  • And, with a single mouseclick, subject critical measurements to a host of SPC analyses, including: Capability, Correlations, ANOVA, Distribution Analysis, Cost of Variability, and many others.

Quality Reports

Many die casting foundries are a link in an extended supply chain, with customers who are themselves manufacturers. As manufacturers, those customers have often adopted progressive quality methods and those methods, in an effort to be thorough, frequently include Quality Reporting standards for suppliers to follow. SPC data is often required on a regular basis in the form of a Quality report or data summary.

Fortunately, the SPC underpinnings that a die casting foundry would leverage to modernize its operations are the same underpinnings needed to meet customer SPC-related demands. Once automated data collection methods are in place, the system should be able to accommodate any external reporting requirement. Specifically, reports with capability studies, Cpk analyses, control charts by date/time, and other summary information should be available on-demand, and they should be capable of being narrowed at runtime by user-defined criteria. Quick access to the right reports results in significant time savings, and reductions in clerical overhead within the Quality department. If a Quality audit is requested or sample data is needed for an investigation, the Quality team can instantly filter historic data and generate detailed data sets that reveal inspection results, compliance to specifications, and a full complement of statistical summaries. Having the ability to prove capability of both parts and processes over time undoubtedly improves customer satisfaction and accelerates business growth.

The Final Cast

SPC projects may not give a die casting machine extra pressure or force during a shot injection. But they will deliver real-time oversight of key measurements, with split-second responses, and they will establish a repeatability that doesn’t let up, arming a foundry with what it needs to really meet modern quality standards. The eventuality of predicting performance and preventing processes from producing parts that are out-of-specification will, with SPC, become the new norm–a norm of higher quality at lower cost.