It is important to use special types of sand for certain types

of castings, including the many different kinds of metals and

alloys. In this example, Humtown uses a chromite sand

from Africa, which causes the casting to chill faster in the

mold.

Foundries Find In-House Core Shops

No Longer a “Core Necessity”

Many foundries outsource cores to gain significant benefits that far outweigh

those of producing cores in-house

he sand core shop is an almost universal facility that can be

sumes energy, compressed air, air scrubbers, floor space and other

found in foundries around the world. At one time considered

resources, yet often times labor is the only cost considered by the

a vital part of the foundry for constructing complex molds -

foundry, when calculating core making costs.

particularly those with passages and cavities – the foundry core

“If you want to learn the true costs of cores, you can get

shop may now be fading into the past due to higher costs, overall

those from an outside core making specialist,” Holden adds. “Not

core quality and production issues.

only do they track overhead completely and accurately, but they

Although many foundries still maintain the classic in-house

also help to keep the outsourcing of cores competitive and afford-

core shop, others are finding conclusive evidence that core making

able. Just considering the foundry’s unidentified overhead, it is

is no longer a core necessity central to their success, and is best

highly possible for them to lower core costs by going outside to a

outsourced from core specialists.

core specialist.”

“For many foundries, in-house core production has been a

Improved, consistent quality

sort of necessary evil that for several reasons is no longer practi-

cal,” says Dick Holden, an industrial consultant with Advanced

Sales Dynamics, Cranberry Township, PA. “I think it’s fair to say

While many in-house core makers are skilled craftsmen, their

that in-house core production is often a deterrent to productivity

capabilities are sometimes thwarted by foundry policies that inad-

and profitability, and could be the source of considerable waste.”

vertently compromise casting quality.

For example, sourcing the optimum sand or silica used to

Lowering core costs

make cores may be unfamiliar or overlooked.

Holden says core specialists such as Humtown Products

Given that foundries are in the business of making and fin-

(Columbiana, OH) use all virgin sand that is consistent in quality

ishing castings, for them to have core shops often creates a hidden

and composition.

source of overhead, Holden says. For example, the core shop con-

“Many foundries recycle sand for use in making cores,” he

Covert mentions that at Humtown core quality is checked

very carefully, and because the firm also has longtime pattern de-

sign and fabrication capabilities, worn or out-of- spec tooling can

be quickly and accurately corrected, a significant value-added ser-

vice to foundry and OEM customers.

Leveraging capacity

One of the main reasons foundries are outsourcing their cores

is faster turnaround time. While foundries are used to outsourcing

cores with difficult configurations, in many instances they inad-

vertently hold back production by making simpler cores in-house.

“Some foundries struggle to make 10 sets of cores per day,”

Covert says, “where an outside core specialist like Humtown can

produce 100 sets of those same cores every hour.” He adds that

turnaround time for the outside core specialist may be a matter of

days to two or three weeks, compared to several weeks or even

Although many foundries still maintain the classic in-house

months for the in-house core shop.

core shop, others are finding conclusive evidence that core

making is no longer a core necessity central to their success,

When it comes to large volumes of cores, the capabilities of

the outside specialists are not lost on many foundries. But Holden

and is best outsourced from core specialists.

says there are many instances when the foundry should not be in

the core business even for smaller volumes because the real estate

explains. “So, there might be a mixture of fine and coarse materials

occupied by a core shop can be put to more profitable use, whether

in it, or it might be coarse this time and fine the next. Without

making castings or for providing space for finishing equipment.

consistency your core results, and possibly casting results, will vary

all over the place.”

Avoiding compliance issues

Holden adds that it is important to use special types of sand

for certain types of castings, including the many different kinds of

Like outside core specialists, foundry core shops are subject

iron and steel, steel alloys, copper, brass, zinc. For example, for

to EPA requirements, some of which are very stringent. Core shops

manganese steel a certain pH property is required, such as olivine

have to scrub all of the air within the department or building be-

sand from Green Mountain, South Carolina.

cause of the hazardous catalyst used to cure the cores. In the case

“If you want the casting to chill faster in the mold, you should

of outside core shops, the entire building must be sealed and air

use a chromite sand, which comes from Africa,” advises Don Co-

scrubbed before it can be recycled. Foundries are held to even stricter

vert, Humtown’s Technical Sales Representative. “Zircon sand is

standards. Because the building cannot be sealed, air scrubbers are

more for steel castings, and much of that material comes from

required for every core-making machine – at very substantial cost.

Florida. Not only do the sand types and quality make a difference,

Even with this equipment, cores continue to off-gas for periods up

but also the types of powder additives. If you want to capture nitro-

to 24 hours, exposing the area to the catalyst, and subjecting the

gen out of a certain kind of steel, you should add the black iron

core facility to EPA compliance issues.

oxide, spherox, or an appropriate powder additive to the sand and

“Foundries already have enough air quality issues to deal

blend,” says Covert.

with,” says Holden. “When you consider the capital investment

required for air scrubbing equipment, the many months it takes to

Reducing waste and machine time

get those systems installed, approved and permitted, plus the tasks

of dealing with continual monitoring, the already marginal ben-

Sand cores that are used to make passages are often very

efits of having an in-house core production facility become all the

intricate. For example, oil pump passages for jet engines have very