2. How good is the chemical resistance?

3. What are some design precautions?

4. What is the minimum wall thickness?

5. What size parts can be cast?

6. How precise can parts be cast?

7. How accurate can the overall cast height be held?

8. What can be done about the low tensile strength?

9. Can ZANITE castings be painted?

11. How can I reduce weight?

12. How can the weight be increased?

13. What do I do about dowel pins?

14. How long does it take to cure?

15. What are threaded inserts made of?

16. How strong are inserts?

17. Can ZANITE castings be machined?

18. Should the edges have a radius?

19. Is low heat transfer a problem?

21. What is the cost per pound?

22. Is EMI shielding necessary?

23. What are some of the benefits of room temperature casting?

24. How much does a mold cost?

25. What material should I make mold from?

26. How long will the mold last?

27. Does the part need draft?

28. How energy efficient is the ZANITE casting process?

ZANITE polymer composite is a formulation of a high strength epoxy, mixed with a blended quartz aggregate filler. In addition, the system includes chemical additives to improve the strength and durability of the composite.

2. How good is the chemical resistance?

Very good. The quartz aggregate offers excellent strength and chemical resistance. The epoxy formulation offers excellent resistance to most common solvents, acids, alkalis and cutting fluids.

3. What are some design precautions?

Things to avoid are thin sections, back taper where tooling must be drawn against the part to be extracted, high tensile loading, shock loading, tapped holes too close to the edge and horizontal surfaces formed by the tooling, thus causing air to be trapped.

The standard ZANITE mixture has aggregate up to ?" (12.7 mm) in size. The minimum section thickness should be at least two times the aggregate size or 1" (25.4 mm).

One of the major advantages of using ZANITE castings is the ability to cast sections of varying thickness without causing internal stresses. Metallic castings require consistent cross section thickness to reduce internal stresses and distortions.

5. What size parts can be cast?

To utilize the ZANITE formulation, the part needs to be at least as large as a bread box, about 80 lbs. (36.3 kg). The largest machine tool base we have cast weighed 70,000 lbs. (31.7 MT). The maximum size part is limited only by the ability to ship the part.

The average size part weighs between 800 and 2,000 lbs (363 kg and 907 kg). Smaller parts can be cast, but these are not the ideal type part for us to produce.

6. How precise can parts be cast?

Part flatness, hole location, hole diameter and feature measurement are all measures of precision. The precision of the cast part is determined by mold design, mold construction and process variables.

Using a properly designed, high quality steel mold, parts can be cast with a flatness of 0.0025 in/ft (0.006 cm/m), and hole diameters of 0.001 in/ft (0.003 cm/m). When closer tolerances are required, or a low cost mold is to be used, tolerances can be achieved using secondary machining, lapping, grinding or grouting processes.

Casting to tolerance is highly desirable as it eliminates expensive secondary operations. By eliminating secondary operations, the delivery time is expedited, reducing work-in-process inventory and allowing quicker response to customer delivery requirements. Deliveries can be days, instead of months as is typical for metallic components.

7. How accurate can the overall cast height be held?

In most cases the height of the part is held within +/- ?" (6.35 mm ). Parts are usually poured upside down, with the top of the mold open. This cast surface (the bottom of the part) is therefore very rough and not closely controlled.

Where the overall part height is of concern, or all surfaces must be finished, a secondary operation (post casting or machining) can be performed. This will add to the cost of the part.

8. What can be done about the low tensile strength?

Most machine tools are subject to compressive loading. Where parts have tensile loading the section thickness should be increased to accommodate the loading. If the section thickness must be kept small, internal reinforcements should be used. These internal reinforcements can be structural rebar, threaded rod, angle iron, fiberglass rebar or any other rigid structure.

9. Can ZANITE castings be painted?

Parts can be painted with any commercial paint, including new water base paints. Priming is not necessary as these parts can not rust. It is necessary to properly clean the surface to remove mold release from the part surface or the paint will not stick.

Most ZANITE parts are not painted. Unlike metallic structures which rust or corrode, ZANITE castings can not rust or corrode and are impervious to most common solvents.

ZANITE castings are typically cast black, white or tan. It is possible to cast other colors, but this requires significant production volume and exact color matching is not possible. The part surface finish will exactly duplicate the mold surface, from high gloss, to matte to textured.

10. Does this material creep?

All materials creep. With proper part design ZANITE parts has a low creep rate. Metallic parts not only creep, but also distort due to internal stresses.

It is important that the ZANITE casting be properly designed and processed. Aggregate sizing and proper compaction is necessary to assure minimal air voids, along with solid aggregate contact, thus minimizing creep.

11. How can I reduce weight?

ZANITE composite has a density of .082 lb./cu. in. (2.27 g/m? ), approximately the same as aluminum. Because the wall thickness will be greater than an aluminum casting, the part weight will be higher.

Part weight can be reduced by casting foam cores internally. This creates a closed box design that provides a stiffer design than open end cores used in metallic castings.

Weight reduction can also be achieved by using hollow structural forms such as steel box tubing. This not only reduces the weight of the part, but it also adds stiffness.

12. How can the weight be increased?

The density can be increased by using a high density filler, such as iron flakes, ceramic beads or iron ores.

13. What do I do about dowel pins?

Dowel pin holes are cast directly into the ZANITE. The cast hole allows a perfect fit with a slight press fit.

14. How long does it take to cure?

The standard cure rate is 18 hours. For very complex or high precision parts, the cure rate is slowed to 24 hours.

15. What are threaded inserts made of?

Tapped holes are created by casting threaded inserts into position. These inserts are produced from steel, plated steel, stainless steel and brass.

Tapped hole locations are determined by the mold, which means once a mold is qualified, subsequent part inspection is minimized.

16. How strong are inserts?

In most instances, the insert is strong enough to allow a grade 8 bolt to be tightened to the proper torque. For extreme bolt loading, the inserts can be anchored deeper into the casting.

The standard inserts have a hexagon external configuration, with a recessed center section to allow anchoring in the composite. Inserts should be kept at least one diameter from the part edge.

ZANITE as cast cannot be tapped. If a tapped hole is required after casting, a hole is drilled and a insert is grouted into position using a template. If tapped holes need to be added during the assembly operation, steel pieces should be cast in the relative location.

17. Can ZANITE castings be machined?

ZANITE castings can be ground using conventional aluminum oxide wheels and coolant to reduce the dust. The surface can also be machined using carbide cutting tools. Secondary machining is not desirable and should be avoided.

18. Should the edges have a radius?

Although radiused edges are stronger, it is difficult to produce steel tooling that will result in radiused edges. Fiberglass molds can be used to produce radiused edges on castings.

19. Is low heat transfer a problem?

Low heat transfer allows the base to resist heat transfer. In the case of machine tool bases, this means distortions due to heat build-up in one section, transferring to distort another section, will not occur. Transient heat loads due to outside doors being opened or sun light coming through a window, will have little effect on the base. Metallic structures tend to distort quickly due to minor heat loads.

Where heat transfer is required, vent holes or internal coolant lines can be cast in place.

20. How does heat effect the part's strength?

ZANITE is made from a thermal setting polymer, so it will not melt. Like any other common material, the strength decreases as the temperature increases. The strength is only slightly reduced up to 160˚ F (71˚ C). Parts can be used up to 250˚ F (121˚ C), where the strength will be approximately 50% of the room temperature strength.

21. What is the cost per pound?

The cost per pound is not comparable to metallic castings as ZANITE parts are cast to finished tolerances, so the cost is for a finished part. Metallic castings are quoted on a cost per pound, but they require secondary machining so the delivered cost per pound is much higher.

Finished ZANITE parts sell for $0.75/lb. to $100.00/lb ($1.65/ kg to $220.50/ kg).

22. Is EMI shielding necessary?

In some instances, supplemental EMI shielding is necessary. This can be achieved using an external shield, cast-in internal shield or EMI paint.

23. What are some of the benefits of room temperature casting?

PVC piping can be cast-in for wire ways, air venting or coolant flow. Oil lines can be cast-in. Cardboard tubes cans be used to reduce weight. Low friction way surfaces can be integrally cast.

24. How much does a mold cost?

Mold cost includes mold design and mold production. Mold design is often supplied free, but can run between $2,500 and $4,500. The mold design belongs to the Zanite Division; the mold belongs to the customer. The mold design effects the part quality, production time and mold life. Polymer casting molds should only be designed by those experienced in the intricacies of the polymer casting technology.

A high quality steel mold typically costs between $6,000 and $90,000.

25. What material should I make mold from?

Molds can be produced from steel plates, aluminum plates, wood, sheet metal or fiberglass. Wood is used for prototype parts for quick delivery. Life expectancy is only one part, although with careful handling several parts can be produced. Tolerances cannot be held, so secondary machining or grouting is necessary to obtain precision.

Fiberglass molds are used for high volume, low precision parts.

Sheet steel molds are used for lower cost, high volume parts. Medium precision parts can be cast in a sheet steel mold, with the proper design.

Aluminum castings are used where the part has an intricate configuration and multiple molds are required.

High precision parts can only be cast using a heavy duty steel mold.

26. How long will the mold last?

The mold life depends on the mold design, construction and handing. A good quality steel mold should last hundreds of parts, with only minor maintenance. Fiberglass molds will also produce hundreds of parts.

27. Does the part need draft?

Draft is not necessary, but it can reduce production time. Cast parts can be produced with no draft, negative draft or recesses. High volume parts should be produced in a mold with draft. The tool construction cost is higher for molds with draft.

Draft should be 2∞per side. Molds that have no draft require complete disassembly to extract the part and therefore have a higher production cost.

The ZANITE casting process uses much less energy than metallic castings. To produce a metallic casting, iron ore must be mined, smelted, melted for casting, and machined to tolerance. ZANITE resins use very little energy to produce and the casting process is done at room temperature.