News - Technical Articles

In-House Blackening System Streamlines Actuator Assembly at Bimba Manufacturing Company Process Integrated into Company-Wide Computerized Maintenance Program.

An actuator product line of thousands of standard models, sizes and styles, many of which require blackening, necessitates a well-planned, smooth operating finishing system. At Bimba Manufacturing Company, rapid growth and a desire to improve quality and delivery led the company to invest in an in-house blackening system which added both capacity and flexibility, while it improved overall finished part quality.

Bimba is a world-leading manufacturer of a wide line of air cylinders, rotary actuators, linear thrusters, rodless cylinders, flow controls and position sensing cylinders. These products are used in machinery and automation of all kinds in many industries. Bimba manufactures and sells these devices to original equipment manufacturers and end users throughout the world. Many of these actuators have customized lengths, bores and other special features. Yet the company is able to manufacture these products to customer requirements without difficulty, according to Bruce Croix, manufacturing engineer at Bimba. To do this consistently, a finely tuned manufacturing operation is paramount.

In-House Blackening System
In-House Blackening System

Bruce Croix said that his company improved its part finishing of components used in its Position Feedback Cylinders. Note these cylinders feature a hard chrome plated carbon steel piston rod with Birchwood Technologies blackened threads and wrench flats.

To meet both delivery and quality requirements, Croix said his company regularly identifies areas to improve, and one that recently received attention was its finishing department.

Production Scale Testing Proves Valuable

Upgrading a finishing line involves both equipment and chemical products, and Croix proceeded in a deliberate manner so as to minimize risk to the company. Since Bimba already owned a process line (albeit an old one) that was still operating, it made sense to use it to evaluate new chemical processes.

"We needed a cold blackening process that worked consistently and was easy to maintain," reported Croix. "We needed a supplier who could provide us with a customized process that would work well for our products and deliver it as we needed it without startup problems. Operator safety was an issue also since we didn't want the problems of a hot oxide line. We knew about Birchwood Technologies so we called them in to see what they could do."

Bimba started using the Birchwood Technologies customized Presto Black process in its existing line, and according to Croix, "It worked from the start, and it worked well. The key is keeping the blackening tanks clean and charged with proper strength formulations. And that was accomplished with fairly simple upfront operator training provided by Birchwood Technologies. Once we got comfortable with the process on our existing finishing line, it was fairly easy to design the new system around that process."

Birchwood Technologies System
Presto Black process

The Birchwood Technologies Systems employed by Bimba have the capacity to blacken batches of carbon steel rods, like those being held by Ron Neis, in seven easy steps that take just 15 to 20 minutes.

Employee Input Helps Design and Fine Tune New System – Initiates Computerized Maintenance Process

Because Bimba involves the eventual operators of the system in the purchasing decision, it makes the startup process a lot easier, according to Croix. "We got their input on what they liked and didn't like about the old and new processes. They really talked a lot about quality issues and how to achieve consistent results. They addressed process maintenance and time to produce parts. They helped to determine optimum tank sizes to handle the range of part sizes in the volumes that our orders require.

"A very important issue for the employees involved with the finishing system was the design of a computerized maintenance program to facilitate its operation. At Bimba, employees responsible for acquiring any new system, process or machine are also responsible for designing the maintenance process to keep it operating and producing products of consistent quality. One of our manufacturing engineers, Ron Neis, worked closely with us to dovetail the blackening process parameters into Bimba's plant-wide computerized maintenance program. The well-defined Birchwood Technologies finishing process was relatively easy to incorporate into this program because it was simple and straightforward to operate and maintain. Our employees' ideas on all of these factors helped to better define the requirements and specifications of the system, and it helped to pre-sell the system to the people who must approve the capital expenditure."

Process Steps Take 15 to 20 Minutes From Start to Finished Parts

Bimba's workers learned to operate and maintain the system in a single day with on-site training provided by Birchwood Technologies engineers. The process steps are as follows:

  1. Clean and degrease in an agitated washer operated at 125°F with 5 to 10 minute dwell time to remove all fabricating oils, coolants, etc.
  2. Rinse in cold tap water.
  3. Prepare Surface for blackening by immersing part in Presto Prep® mild acid conditioner at room temperature for 1-1/2 minutes dwell time.
  4. Rinse in cold tap water.
  5. Blacken in Presto Black® PBR at room temperature; 3 to 4 minutes dwell time.
  6. Rinse in cold tap water.
  7. Seal in Sheath WS-12 rust preventative.

Birchwood Technologies Blackening process

Timers and flashing indicator lights make it extra easy for operators to use the Birchwood Technologies Blackening process. It also takes the random guesswork out of the process steps so parts have a high quality finish every time.

The entire 15 to 20 minute process requires just one operator and utilizes just 2 heated solutions with all other process steps done at room temperature. The seven process tanks vary in size from 40 gallons to 105 gallons. The seventh tank also acts as a drop-off station for the process hopper after which finished parts are moved to an area for a light oil application. A manual hoist is positioned above the full width of the finishing system so that the operator can easily move larger part loads in batches through the series of tanks.

Croix estimates that about 2000 parts of various sizes are finished each work day. The majority of these are carbon steel rods, many with threaded ends. They range in length from 1 to 36 inches and in diameter from 1/8 to 7/8 inches. On average, the system is operated for 4 hours or less, Monday through Friday. The system's heaters are connected to timers which operate automatically so the system is ready to go when the work shift begins. The system automatically shuts down each day unless an operator intervenes to run it for a longer period.

Croix reported the only time a problem was encountered was when an operator forgot to replenish the chemical solution. A simple titration test was done to secure the correct chemical balance and the system was operating properly without any significant loss of processing time.

Birchwood Technologies Blackening process

Bimba's tanks were manufactured by Hardwood Line Manufacturing of Chicago. Note overhead hoist brings unfinished parts to the line and after finishing moves parts to assembly cells

Once the Birchwood Technologies chemistry had proven itself in the old process line at the Monee, Illinois facility, a new tank line was purchased which incorporated all the processing suggestions offered by the operators. From there, it was an easy step to justify a second installation, identical to the first, to be located at the new Manteno, Illinois facility. The two lines operate simultaneously, with the Manteno facility dedicated to higher volume sizes, while the Monee line processes specials and lower volume runs. With both lines operating, all of the production can be blackened on a same day basis without interruptions.

"Making both finishing system changes was fairly easy," reported Croix. "We did it at Bimba in the same way as we would add any new piece of capital equipment. It's a good process and a good system."