Cleaning deep cavities in a cast iron or light metal casting quickly and cost effectively has always presented a challenge to companies in the automotive and off-highway vehicle industries. Complex problems abound when foundries manufacture engine block and head components where volume production is critical to the assembly of engines. While the size and weight of these parts pose one set of problems, the presence of blind passages and internal cavities in blocks and heads make the cleaning job much more complicated.
Historical methods that have been used to clean blocks and heads include high production cage designs. With these systems, parts designed with different dimensions cannot be cleaned without substantial time loss resulting from tooling changes. Robotic cleaning systems have been developed; however, the ingress of shot into the fragile components can cause premature failure. This occurs because the sealing of the blast compartment with sunburst seals cannot fully contain shot on a sustained basis. In addition, size and weight of cast iron parts and the presence of sand in the system present more issues that may limit the use of robotics.
Years ago, Pangborn® recognized these system limitations and, therefore, understood the needs of its customers in the global market of engine component manufacturing and developed a better solution. Pangborn’s customers have benefited from installing a gripper machine that offers high volume production and minimal or no-tooling changes while processing a large volume of different size and configuration engine blocks, crankcases, gear housings, heads, and other vehicle parts. Engine blocks, some as small as 4 cylinders and as large as V10 diesel, have been successfully cleaned using Pangborn’s gripper techniques. Because of this flexibility, Panborn’s gripper is now the market preference around the World.

The “Up-Front” Study

Tailoring the gripper machine to each customer’s unique requirements and specifications begins the same way as every other project at Pangborn®. From the beginning of the project, Pangborn® and its customer undertake an extensive evaluation process. Customer expectations are examined and site layouts and designs are scrutinized to make sure that the machine configuration selected is right for the job.  In accomplishing this, parameters for the application are determined through discussions between customers’ technical experts and Pangborn’s experts.  Pangborn® engineers perform in-depth studies and utilize extensive project management techniques to ensure that a system can perform the job required by customers.
Pangborn® takes pride in having the capability to manage large and complex projects that require considerable "up-front" study. Technical issues that require evaluation include size, weight and critical areas of the component to be cleaned. How a component enters into the blast area, determination of the optimum blast stream, production output, and exiting the blast system are all necessary considerations to address when designing a successful system. Electrical apparatus options, PLCs, hardware components, maintenance procedures, plant power specifications, floor and ceiling space, local ordinances, ergonomics, work flow, life cycle costs, and safety requirements are studied on a routine basis to ensure success. The goal of the study is to determine cycle and dwell times, cleaning and abrasive retention specifications, and internal passages cleaning. Pangborn® undertakes a project only when it knows that a cost effective solution is possible.

Pangborn’s Customer Technology Center - A Huge Step to Success

It is necessary that the designs and concepts developed with our customers be put to the test. Pangborn’s Customer Technology Center (CTC) is fully equipped with everything that is required to test new approaches for blast applications. Designs and concepts are subjected to real-time testing using actual parts supplied by our customers. Prior to making a major capital investment, testing allows the customer to see first-hand if the application approach and design is effective in cleaning their parts.
The CTC is vital to a successful gripper project. With the engine blocks, or other samples provided by the customer, an engineered gripper simulator is set up in one of Pangborn’s CTC test machines and the samples are blasted to obtain actual results, not computer simulated results. The customer and Pangborn® can test different processes to find one that will meet their final product requirements. Wheel designs and positions, line and rotation speed, and abrasive are all determined based upon simulations in the CTC. Parts can be sectioned to guarantee that specifications are met.
Pangborn® Corporation’s CTC is used for much more than just testing gripper applications. The CTC can be used by the automotive industry to test foundry, die cast, axle forging and many other blast applications. Pangborn’s customers also use the CTC to test descaling, peening, air blast and many other industrial applications.

How the Gripper Works

Now in production on two continents and in three countries, each Pangborn® gripper machine has similarities. Both have two compartments separated by a turnstyle partition - one for loading and unloading, and a second for blasting. Using a two-compartment configuration allows increased production output.
Typically, parts are conveyed to the machine and placed on a load conveyor. The hydraulic load/unload mechanism is equipped with positive stop location to accurately position parts in the gripper. The system guarantees exact placement of every casting. From the first compartment, the part is raised and transferred onto the gripper where jaws are hydraulically manipulated to hold the part and prepare it for blasting in the second, or blast compartment.
The gripper machine is provided with up to ten Rotoblast® wheels depending on the production requirements and what is learned during the CTC testing. The Rotoblast® wheels can be designed with bearing and spindle drives or direct drive motors. Both have advantages and Pangborn’s experts help customers determine which drive solution is best for their application.
The advantage of using a spindle driven wheel is that the bearings are larger and provide higher system capacities. The labyrinth seals used with bearing and spindle drives provide excellent protection from shot entering the bearings. Another advantage of a spindle driven wheel is the added flexibility to increase or decrease the abrasive velocity simply by changing the sheave on the system. This flexibility allows customers to easily run different sized parts or differently conformed parts, entirely.
The direct drive wheel is often chosen because of its compact nature. It also operates with less maintenance because there is no spindle to grease, and guards, sheaves, and V belts are not required.
The type and number of Rotoblast® wheels, horsepower, and location are determined as a result of CTC tests.
System controls play an important part in the operation of the gripper. Machine functions are controlled by a PLC tailored to the customer’s requirements and specifications. Closed loop hydraulic proportional controls are used on all machine movements for smooth, repeatable accuracy. A touch screen Human Machine Interface is used for all control functions, as well as blast sequence modification, system monitoring and error reporting.  Available Ethernet compatibility can be used for additional monitoring, diagnostics and reporting.

Area Discrimination

The gripper employs a simple but sophisticated design. The jaws of the gripper clamp the part and a turnstyle rotates it. The electronically controlled abrasive gates open and media flows to Pangborn’s Rotoblast® wheels to clean the part. The jaw rotation ensures that all sides and passages of the part are exposed to the abrasive. This rotation is controlled by the PLC and can be programmed to continuously rotate or stop where an area will be in the blast stream for an extended period. The ability to concentrate a blast stream in an area enables the system to clean complex internal passages contained within the part.
The gripper jaw rotates 360 degrees clockwise, stops, and rotates 360 degrees counter clockwise. The design ensures that cleaning is done to the customer's specifications and facilitates shot drainage.
If shot carry-out is a problem, the gripper jaw can continue to rotate to further evacuate the abrasive from the part.
When the blast cycle and shot evacuation process is complete, the part will be transferred to the first compartment and automatically unloaded as another part is automatically set in the gripper, resulting in an unattended continuous process.

The Preferred Design

Because engine blocks and heads require complex blasting applications, the Pangborn® gripper has become the market-preferred solution.

The gripper increases production because it minimizes tooling changes. The "up-front" evaluation process provides designs that allow for maximum up-time of the system. In addition, Pangborn® technology provided in the Rotoblast® wheels reduces cleaning cycle time. Productivity is also increased due to the simultaneous processing of multiple pieces.
Lowering maintenance costs has become the benchmark of the Pangborn® gripper. Wear resistant materials in the blast compartment and wheels increase the life of parts; therefore, lowering operating costs. Improved maintenance characteristics increase machine up-time, which is vital to maximizing our customer’s sales and production figures.
Additional applications where the gripper concept can be used include manifolds, transmission cases, compressor and gear housings, and other components where the ultimate flexibility is required while gaining high production output with low maintenance costs.
Since 1904, Pangborn® Corporation based in Hagerstown, Maryland, USA has been a world-leading manufacturer of complete surface preparation systems, equipment and services. Because of our worldwide reputation for excellence in design, engineering, and service, the automotive industry, as well as many other industries, trust Pangborn® to find the answers to higher productivity, peak efficiency and lower maintenance of their blast equipment.

Pangborn Corporation
580 Pangborn Blvd.
Hagerstown, Maryland, USA
Tel. +1.301.739 3500
E-mail: info@pangborn.com
www.pangborn.com