Automated Heat-Treatment Monitoring System
DynaBil Industries is a manufacturer of sheet-metal components for the aerospace industry. They supply parts to major aerospace manufacturers according to customer specifications that describe heat-treatment process parameters (time/temperatures) and requirements for non-destructive testing (hardness/conductivity). In addition, DynaBil is required to follow Nadcap (National Aerospace Defense Contractors Accreditation Program) guidelines, an industry-managed program for special processes whose goal is to increase the quality and uniformity of products. Since process specifications vary slightly for each customer and Nadcap requires documentation detailing the conditions of each process, furnace setup and monitoring is quite complicated and time consuming for an operator. Final testing of parts and report generation had become difficult and time consuming for the oversight personnel involved as well.
System DevelopmentA group of engineers from DynaBil and a consultant from Wing Tech II, LLC evaluated this problem and have created a system that encompasses lean-manufacturing strategies and improves efficiency. The goal of this project was to increase the capacity and efficiency of equipment as well as to create a system that minimizes operator errors and reduces the process setup times.
Higher productivity has been achieved by fully automating the setup of the furnace (controller set point, allowed temperature range and process time) depending on the parts in a particular load. The parts for a load are entered into the system using a bar code on the traveler document associated with the parts (Fig. 1). This process “batch” creation calculates the most efficient temperature set point and timer settings and validates that the requested parts can be processed together (i.e. sufficient overlap of the process temperature and time ranges). The process-create application will not allow the operator to add parts to the “batch” that cannot be processed with previously added parts.
This automatic setup eliminates the time and possible transcription errors involved when an operator manually looks up the required specifications then checks for the proper overlap in times and temperatures. Several process loads may be entered into the database and queued for later use. The operator can then select a queued process “batch” to load into the furnace on the local PC and the appropriate parameters are placed into the control system.
System CapabilityThe Data Acquisition and Control System, based on Lookout© software and FieldPoint© hardware from National Instruments and an ODBC-compliant database (currently Microsoft Access), records the following process parameters:
- Certified operator’s ID
- Load parameters (job/lot/quantity) and process requirements (time /temp)
- Time and temperature of furnace when load was placed into working zone
- Time and temperature of beginning of process (recovery time)
- Time and temperature of end of process
- Quench delay and quenchant temperature (if applicable)
- Time and temperature when load was moved into and out of the freezer (if applicable)
- Requirements for testing (ranges of hardness and conductivity)
- Results of tests
The Data Acquisition and Control system was developed using a client/server architecture where the server interfaces with the data-acquisition hardware, performs the temperature control functions, sequences the process as required and posts the acquired data to the database. It also performs alarming if any temperature transitions out of the specification range. The client is essentially the operator interface to the system. It allows the operator to create (queue up), select, start and abort processes. The main display is an overview screen that shows the status of all of the ovens in the heat-treating area as well as a trend graph where the operator can display a selected oven’s temperatures (Fig. 2). The operator can zoom and pan the trend and show either historical or current data.
The client application can be deployed in multiple locations on the manufacturing floor. This facilitates access by more than one operator and in situations where ovens might be located at a distance from one another.
The storage time in the freezer is monitored by a separate client application with a screen that contains specific information related to each work order and also displays a color-coded status about remaining storage time of each work order (Fig. 4). This visual information is very useful in creating a work schedule. Again, this client can be deployed to multiple locations.
All of the recorded data is contained in an electronic database and can be used to track any work order on the manufacturing floor. A final report is generated to display requirements and actual data at every step of heat-treat operation, storage time/temperature of parts in the freezer and results of all tests performed on parts in the work order.
SummaryThis system was implemented last year and has fully accomplished the project’s target. Originally designed for heat treating of aluminum only, the system is currently being modified to include heat treating and forming of titanium and steel parts. Efficiency of our heat-treat operations has improved significantly (approximately 25%), and the accuracy and repeatability of the entire process exceeds Nadcap and customers’ requirements while providing an audit trail for each process. IH
For more information: Contact Donald Chickering, WingTech II, LLC, 90 Hillis Terrace, Poughkeepsie, NY 12603; tel: 845-462-6001; e-mail: WingTech@optonline.net.