Most food processors would jump at the chance to implement a company-wide statistical process control (SPC) program. Tree nut processor Blue Diamond Growers of Sacramento, Calif., is one of the rare companies that has done just that -- and with welcome results.

Blue Diamond recently completed a five-year program to implement SPC as part of an internal, company-wide line certification program. In addition to making process improvements and reducing variation, the SPC program's objective was to determine process capabilities for the company's various lines. "Meeting customer specifications if very important to us," said Kurt Huebner, project manager for the SPC implementation team. "SPC is a powerful tool for telling whether our processes are capable of producing finished goods [that meet] our customers' requirements. Crop input differs from year to year and knowing our process capability allows us to help customers make changes to accommodate the current crop."

As the world's largest tree nut processing and marketing company, Blue Diamond processes up to 800,000 lbs. of raw almonds a day at its Sacramento plant. The process begins with an inventory system, followed by shelling, and then a main production line. The production line sorts out foreign materials, then machine-grades the nuts into eight different sizes utilizing electronic sorting machines to eliminate insect and mechanical damage. Next, line operators perform a final sort and inspection before the product is packaged in bulk for customers or sent to the company's manufacturing division for blanching, slicing, dicing, cooking and packaging in cans or foil packets. All together, the company has 60 production lines.

To launch its SPC program, Blue Diamond first needed to select an appropriate software package. "We needed one that could perform the statistical analysis we needed, work with our existing systems and be easy for people of all abilities to use.'' After an exhaustive, year-long search involving a team of process engineers and informaton systems staff, the company selected NWA Quality Analyst from Northwest Analytical Inc. At the time, the package was already being used by Blue Diamond's quality control department. "We chose NWA QA because it was easy for non-engineers to use, and it had the functions and statistical tests we needed," said Huebner.

To customize the system, Blue Diamond created a client server application using Visual Foxpro and Microsoft SQL Server. The Visual Foxpro application simplifies data entry and exports data from the SQL database to NWA QA in order to generate control charts and histograms.

Line certification

With the main software tools ready for use, the team began certifying the plant's 60 line operations. Each required six months for certification. To begin, the certification team set up a cross-functional team of operators, production supervisors, and QC, sanitation and maintenance representatives for each line. The cross-functional team's first step was to reduce variability by standardizing the line's work procedures. Once procedures were established, all line personnel began learning computer skills and the basics of SPC. Using NWA Quality Analyst, workers learned how to interpret control charts and histograms, as well as how to identify special causes of variation, tell when the process was in statistical control. As part of the training, they documented special causes and developed corrective action loops.

After instruction was completed, each line was audited to ensure team members understood -- and used -- the procedures. Separate audits were conducted for work instructions, SPC, sanitation and maintenance. Those who failed the audits received further training and were then retested.

With all lines certified, Blue Diamond now tracks a huge number of process variables, such as machine settings, yield, throughput, product temperatures, moisture content, pass/fail tests, nut sizes and grade information. Test data include roast color, slice thickness and size, and granulation. "We're dealing with huge amounts of data," Huebner said. "The typical line is handling about 200 data points per shift.

The plant uses NWA Quality Analyst to check process parameters in real time, and generate big-picture views of processes over time. The quality control department uses the software to produce reports on finished goods to assure customers the product meets specifications.

Another major benefit is the program's positive impact on customer relations. Before the line certification program, customers visiting or auditing the plant worked primarily with the quality control department. Now they spend much of their time directly with the operators, getting a hands-on view of the process. FE

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