Purchaser's notebook: how to buy the right core machine.
With its patented modular concept, the Combi-Core (DISA Technologies), produces coldbox cores with either horizontal or vertical tooling. It features a unique extruding process that extrudes sand into the corebox, resulting in fewer vents, the ability to extrude sand parallel to the parting line and uniform core densities. It is designed for foundries requiring accurate, high-quality cores for medium and high production runs.
This 24 VSTB coldbox core machine (Gaylord Foundry Equipment), automatically ejects cores from tooling after each cycle. Core weights of ounces to 75 lb may be accommodated. In addition to this installation at Reda Pump in Singapore, others include Tonkawa Foundry, Tonkawa, Oklahoma; and Ross Aluminum Foundries, Sidney, Ohio.
Compatible with all hot or coldbox processes, the GF-4040 (George Fischer Foundry Systems, Inc.), features automatic tooling change, stationary corebox, continuous clamping, shuttle head design, horizontal parting, full enclosure, automatic unloading and easy sand magazine cleaning.
The CBH-30-CC Flexiblomatic (Beardsley & Piper) is a fully hydraulic unit that features clamping of tooling throughout the cycle, quick change tooling devices and diagnostics. Designed to produce coldbox and oil sand cores from 50 - 300 lb, it is designed for high production foundries or those with high production core work. Units installed at Neenah Foundry., Neenah, Wisconsin; Doehler-Jarvis Casting, Greeneville, Tennessee; and General Motors, Toluca, Mexico.
The HBS-3040 (CMI-Equipment & Engineering, Inc.) is a new single station, horizontally parted hotbox core machine. With a 200 lb blown core capacity, it features hydraulic squeeze to 120,000 lb clamp force and quick change of the entire tooling stack. It is most suitable for water jacket cores.
The Quikore CB-300-TC (Equipment Merchants International, Inc.) features continuous horizontal clamping all hydraulic operation, low profile blow head and quick change of tooling for producing coldbox cores. Its clamp mechanism maintains high pressure to close the cope to the drag throughout the process, trapping pressure and turning it inward for a higher density core. Designed for medium to large foundries requiring high production needs, its installations include Ford Motor Co., Cleveland, Ohio; Ford Motor Co., Windsor, Ontario; and John Deere Foundry Div., Waterloo, Iowa.
For producing coldbox, warmbox, hotbox and shell cores, the PGV-R series (Peterle, Inc.) offers short cycle times and rapid tooling changes. Using one mobile and two stationary corebox halves, production continues on the vertically split machine while cores are being removed. Programmable controls and hydraulic actuators provide automatic operation.
The 315 ES (Roberts Sinto/Shalco Systems) is a vertically parted core machine with automatic core discharge conveyor. Producing either cold or hotbox cores, it features a programmable controller, quick tooling change and variable tooling adjustments. It is ideal for high production of valves, fittings, small components and electrical fittings. Installations include: Appleton Electric, Appleton, Wisconsin; Moen, Inc., Elyria, Ohio; and Crane Co., England.
The Bicor Disco 3 coldbox unit (IMF North America, Inc.) processes horizontal or vertical coreboxes at the same time. It is designed for foundries with short production runs that require frequent corebox changes. Units installed at Technocast, Orrville, Ohio; Goulds Pumps, Inc., Seneca Falls, New York; and Donsco, Inc., Wrightsville, Pennsylvania.
The CoreCenter (Laempe + Reich) combines coremaking, sand mixing, sand transportation and gas generation all under a single process controller. Compatible with all gas-cured processes, these units offer a six-part horizontal/vertical tooling orientation and are available for job shop to high production foundries Units installed at Waupaca Foundry Inc., Waupaca, Wisconsin; Ford Windsor Aluminum Plant; Windsor; Ontario; and Citation Corp. foundries.
The SHA (Loramendi, Inc.) accepts horizontally parted core boxes for use with all binder systems except self-hardening. It is designed for low and high production foundries using metal tooling, and is also used in key-core systems. Installations include: Ford Motor Co., Cleveland, Ohio; GM Powertrain, Defiance, Ohio; and Mercedes-Benz, Stuttgart, Germany.
The RC EuroCor (Redford-Carver Foundry Products Co.) coldbox shooting machine is compatible with vertically or horizontally parted coreboxes. Designed for high core production, the machine features a powerful coaxial shoot head with infrared fill control. Tooling handling, core handling and cleanout are mechanized. Installations include England's Rover, Ford, Nissan and other automatic foundries. First U.S. installation at Honda of America in 1994.
Coremaking is considered by many as the most complex of foundry operations. Here's a map to follow for coreroom modernizations.
Because very few metalcasting operations produce the same mix, size, shape and volume of core-containing castings, coreroom equipment requirements are unique to each foundry.
If there are many different types and volumes of cores in a shop, planning and scheduling core production becomes complex and difficult to understand. Restrictions in a foundry's capability to produce enough cores to meet its molding line requirements result in the coreroom - in effect - scheduling the foundry operation. Obviously, this is undesirable and costly for any foundry in its drive to function competitively in today's just-in-time environment.
Planning and engineering a complex core facility are much more difficult and time consuming than for the melting or molding areas. The equipment planning, layout, selection, installation and operation processes involve a team effort of all the people working in the core scheduling, producing, molding, designing and engineering areas.
This article discusses selection processes and provides checklists of items to consider for a core machine purchase.
There are three major types of foundries: low-volume job shops, medium-volume job and captive foundries and larger high-volume units. The latter includes some highly automated job and captive track, automotive and agricultural foundries.
Each of these major categories have distinct differences in the selection of core machines. The small job shop may want to go from hand coremaking to a single semi-mechanized core machine. The medium volume foundry may desire to go to an automated core machine that includes sand mixing, PLC control and environmental enclosures.
High volume shops may want highly automated coremaking cells that include automated stripping, definning, gluing, dipping and drying that may be integrated with robotics handling systems. This may also incorporate placement of cores into a mold. Advanced systems may have computer monitored vision systems to determine scrap in operator-free coremaking centers.
The secret is to balance the needs of the foundry based on its size and core production requirements. This formula includes technology, process, volume, environmental requirements and economic capability.
Core Selection Process
Not all coremaking selection procesSes require a detailed analysis. The key is to pick and choose what is needed to meet the foundry's requirements.
The selection process is sometimes driven by the casting requirements. For example, an automotive head water jacket core may best be produced in a hotbox process to optimize core strengths during pouring, as well as breakdown and shakeout properties. The core needs to resist burn-in, which is difficult to remove in the internal passages.
Converting to a different core process can be difficult to justify in lieu of the large numbers of coreboxes involved in many foundries. This is especially true in job shops and where service parts are involved. It may be best to keep one core machine to run the more obsolete core process than to change core machines or processes. Another alternative is to outsource the parts that no longer fit the foundry niche.
Before beginning any coremaking modernization, foundries must look at their processes. When reevaluating your foundry's current processes or looking into switching to an alternative coremaking process, there are many items to consider. The key is to find the process that will best fit the making of quality castings for your foundry's niche area.
To make a wise decision you must confirm your foundry's needs in these areas:
Production - On low to mid volumes, a manual coremaking operation or simple core machine may be adequate. High volume corerooms may require an automated core process. In addition to the volume of cores, the length of the production run is also an important factor.
Core Data - It is critical to examine the core families to be produced, the number of cores per any given casting, the core size and subsequent detail, and dimensional tolerance requirements. Also, the number of cores that can be produced on the corebox for any given process should be determined.
Casting Information - The foundry should examine its metal requirements and shakeout properties, surface finish requirements (shell offers an excellent surface finish), level of burn-in sand resistance, core to metal ratio, coating and drying, grinding and gluing, and special additives and venting requirements.
Miscellaneous- Projected scrap rates, core shelf life (coldbox cores pick up moisture, while shell cores can be stored for lengths of time), and ease of incorporation with existing core processes should be addressed.
Labor - In determining how much it costs to produce a core by a certain process or machine, the foundry must determine: manning requirements (oil sand is labor intensive), cost (of a fully loaded machine), maintenance capability, and skill and training requirements.
If you choose to select a fully automated process, you will remove your labor costs. In an era when many foundries are experiencing real labor shortages, a move toward core automating could free up labor for other foundry operations.
Binder - Foundries must evaluate their binder use, process control requirements (temperature, moisture content, etc.) and resin content. High binder costs may inhibit certain processes.
Sand - In researching alternative processes, types of sand (for shell, coldbox, hotbox processes, etc.) must be examined. Included in this evaluation are sand tonnage requirements, the sand's local availability, cost of new sand (and make vs. buy costs of shell sand), sand fineness and quality, and disposal costs. The ease and capability of reclamation must also be studied, as well as the sand's compatibility when reclaimed. It may be desirable to reclaim one sand type for reuse purposes, rather than attempting to reclaim different types back into the system.
Existing sand system equipment must also be considered. If your foundry is currently using only shell cores, for instance, you may want to purchase one coldbox machine.
Tooling - Can existing tooling be adapted for a new process, if needed? What are core quality requirements and box designs? Will new, high-cost state of the art metal tooling be required (as opposed to wood or plastic)?
The best time to look at process conversions is during new part studies so that if new tooling is needed, costs can be amortized up front. The cost to convert tooling from one process or machine to another is great - in some cases it can overshadow all other criteria.
A common pitfall lies in selecting a new process where the tooling conversion cost is significant and, therefore, limits the machine use on start-up.
Environmental - Present and future environmental requirements must be considered. Emissions capture capability and scrubbing requirements for odor in the plant and neighborhood for various processes must be evaluated. Employee health and safety must also be considered.
Competitiveness - With any process or machine change, the foundry must reevaluate its niche and expertise, and answer the question, "Do we have the knowledge to run this process?" Quality, dimensional tolerancing and production costs of different coremaking processes must be evaluated. The foundry must also take a careful look and determine whether it can remain competitive in the industry with its current core processes and equipment.
Capital availability - Even when all other factors have been addressed and the long-term cost justification has been made, the initial capital must be available to invest in the new core process.
Core Machine Selection
Core machine selection varies for different core configurations, sizes or weights. A job shop making 25 cores weighing 50 lb each has different criteria than a shop making small pin cores. The low volume, large core shop needs to produce a good core on the first machine cycle, with low scrap and have a reasonable corebox change time.
For instance, if a foundry making only 25 large cores before changing the box is unable to produce a quality core on its first attempt, it has lost all the production costs that went into the sand, resin and catalyst to produce that core.
One machine may run many different coreboxes and lend itself to having both vertical and horizontal parting lines. Core machine cost in this case may take a secondary position to other process and operating criteria.
Diesel block and head foundries have their own diversified core machine requirements. These include production of small, medium and large cores that may go into complete assemblies. They may have complex core storage, inventory and staging requirements. It is still ideal, however, to make all of the cores and place them in the mold to pour on a just-in-time basis.
Planning core machine requirements and capital costs, vs. corebox changes and core inventory involves trade-off. Detailed analysis is required to come to the best solution for a given application. Is it better to buy more core machines or increase storage and inventory (cost) requirements?
An analysis of production requirements over a minimum of three months is needed to get a representative sample. One year analyses are preferred.
Determining your production requirements will allow you to:
* Select processes and equipment that will optimize production at maximum as well as average demand.
* Analyze to see if the majority of the value of the castings is produced from a smaller percentage of casting group. The old 80%/20% (80% of the work comes from 20% of the orders) role may come close to actual requirements in this analysis. If this is the case, one needs to define core machine requirements into two categories that include high- and low-volume runners.
* Evaluate to see if the extremes of the product range fit the foundry. One might consider eliminating part numbers that don't fit the facility or are unprofitable.
* Select a core machine that complements the casting volume requirements. Analyze how much the machine will be used. It is unwise to spend a lot of capital on equipment that is not fully utilized.
One should perform an activity-based costing analysis on total core costs, including job change preparation and time. It is not unusual to find this is a key area in the foundry that is not profitable or making the desired profit.
Seize the moment to adjust prices or realign your product mix to fit the foundry niche. This analysis will help decide the direction on pricing, part divestiture or purchase of capital core equipment to improve total foundry profitability.
Other areas useful in analyzing coreroom costs are sand usage, scrap and spillage. One should calculate the percentage of core sand coming into the plant that actually makes it into production of the net good castings shipped. In the past, factors such as spillage have resulted in only 35% of sand going into the core operation making its way into good castings shipped.
The answer may be surprising and costly with today's transportation and disposal costs. One can use this information to select and justify core processes and machines that minimize sand use, optimize cost savings and plant profitability.
Core cells contain all of the equipment required to produce and handle cores. These include an automatic system for raw sand delivery, metering of sand and additives, mixing, delivery, blowing, curing, automatic pick off by manipulators, defining, core assembly by gluing or interlocking, dipping, placement for drying oven, transfer and queuing, and final placement into the mold.
State-of-the-art core equipment may have a high initial cost, but pay dividends in reduced total core costs for medium and high volume foundries.
Selection of the right core process and equipment is critical to making a quality casting in the molding department and not spending excessive time and labor in the finishing department to maintain foundry competitiveness.
Issues in Machine Selection
Once the process has been determined, the following issues must be considered in selecting the appropriate machine.
* Cycle rate (net cycles/hour) - This includes the blow and cure times, and the strip time to remove the core from the box.
* Good core the first time.
* Corebox change - Does the unit offer manual change? Automated change of corebox, blow plate, gassing plate and ejection plate? In changing jobs, does it offer quick change capabilities? How easy is it to change coreboxes? Are there special preheat requirements?
* Corebox size.
* Core weight range, density capability and quality.
* Number of cores per box.
* Which core machine was the box designed to run on? Is it readily adaptable?
* Operating shifts.
* Corebox parting - Is it compatible with horizontal or vertically parted tooling? Does it have capability to handle both?
* Box filling machine design (blowing, shooting, extruding).
* Clamping - Is clamping controlled by an air, hydraulic or electric operation? Does the tooling stay clamped throughout the entire cycle?
* Flexibility - How flexible is the machine in using different boxes (especially in job shop)? Will the machine's capacity be filled by other work?
* User friendly controls - Does the machine offer PLC or touch screen controls? Units are available that are "interconnected by the data highway" and offer diagnostic control and full system integration that don't require operators.
* Material handling at machine - How well are sand, resin, catalyst and gas generation systems handled? How easy is draw and ejection accomplished?
* Core handling away form the machine - After cores are produced, do they need to be manually removed? Or does it feature pick and place unloading or unload onto a tray or belt? Are robots used?
* Adaptability of new equipment to core production cells.
* Workplace ergonomics - How well can the operator operate, blow off and clean the machine and its cores?
* Environmental - How well does the machine capture emissions at the machine? Does it eliminate leaking? How severe are total fumes and odors in the work area?
* Maintainability - How easy is it to maintain the unit?
* Service - Service issues include: spare parts and availability, delivery capability, technical staff skills and availability, service cost, and capability for turnkey installations and start-ups. Also, in certain urgent conditions, a decision may be based on how fast a supplier can deliver the equipment and get it up and running.
* Machine uptime.
* Ease of cleanout - What does cleanout of magazine, blow plate, blow tubes and vents entail?
* Core sand spillage.
* Compatibility with mixer - Can your current mixer serve the machine at volumes needed?
* Capital cost.
Foundry Audit, Manufacturer Interview
Before any decision can be made, the foundry must audit its core needs. A foundry must understand:
* type of cores produced and at what volume;
* how many shifts the coreroom operates;
* core order quantities;
* core weights;
* processes used;
* corebox sizes;
* job change frequency and run times;
* ideal job change frequency.
With this in formation in mind, a number of other factors will have a role in unit selection. This is a checklist of additional steps to take when meeting with a core machine manufacturer for your foundry's specific requirements.
* Can the existing tooling be reused be used on the machine, or is there a cost effective way to convert the tooling? How can new or revised tooling costs be kept as low as possible (wood, plastic, simple metal)?
* Can tooling be redesigned to simplify production requirements? How can the machine's features be used to simplify tooling design (i.e., can a part that is made with loose pieces on a horizontal box be produced more cost-effectively on a vertical box with mandrels?).
* Perform a group technology analysis to determine what cores fit standard core machine sizes.
* Identify the number of machines required by size and loading. Avoid the trap of selecting the machine and then justifying the need.
* Calculate job changes, job change times and hours run on new core machine.
* Look at economics of process change. Areas to consider are increase in production rates; surface finishes; core shakeout; core handling, transportation and storage; and total resin per core (a hollow shell core at a 4% resin content may be cheaper than a solid coldbox core at a 2% resin content).
* Review process control. This area includes: repeatability each time core is run; ease of core process control for the operator; training required; PLC control and storage of parameters in logic; whether process control is built into the machine; ease of core removal and manner of presentation of core.
* How precise is control for verifying resin content, calibrating various catalysts and maintaining constant catalyst proportions.
* What is the ease of installation and time required? Does the unit arrive prepiped and prewired and with foundations? What does start-up service entail? What type of training and documentation are offered? Is it user friendly for operator and maintenance to learn?
"Modernizing Coremaking," C. Doerschlag, Alb. Klein Co., Inc.
"Coreroom Modernization," W. Zachary, Redford-Carver Foundry Products Co.
The author wishes to acknowledge Harry Reich, Laempe + Reich, William Martin, Disa Technologies, Inc., Art Gibeaut, Iroquois Foundry Co., Browntown, Wisconsin, Michael Gallagher, Gallagher & Assoc., Spring Grove, Illinois, and the Citation Corporation staff.
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|Author:||Planson, R. Joe|
|Date:||Mar 1, 1995|
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