What is lathe cut alloy?

What is lathe cut alloy?

Lathecut, spherical or spheroidal powders can be produced in which the manufacturer alters the ratio of metals at the melting stage. Hence the resulting alloy particles are similar in shape and size to conventional alloys but simply contain a higher copper content. These are single-composition, copper-enriched alloys.

What causes amalgam to expand?

Contact of moisture with the zinc caused the formation of hydrogen gas within the amalgam, which caused it to expand. Delayed expansion could cause the restoration to expand beyond the cavity walls, causing cracking in the adjacent enamel.

What causes delayed expansion in amalgam?

Moisture contamination caused delayed excessive expansion and deterioration of the physical properties only with the non-high-copper lathe-cut alloy amalgam containing zinc, but not with the new high-copper amalgam and the non-high-copper spherical alloy amalgam containing zinc.

What is Mercuroscopic expansion?

Expansion that occurs due to reaction of Hg with alloy components is termed primary expansion or mercuroscopic expansion. Expansion that occurs after 1 to 7 days due to moisture contamination during trituration or condensation before the amalgam mass is set, is termed secondary expansion or delayed expansion.

How do lathe cut records sound?

Lathe-cut records are made by cutting micro-grooves into a polycarbonate disc using a record lathe. How do they sound? The sound reproduction is not as accurate as a vinyl pressing and there is some surface noise, comparable to a flexi-disc or an old 78, if you remember those.

What is setting expansion in amalgam?

During the initial setting reaction, commonly expansion occurs due to matrix formation, whereas contraction is the result of a reaction between the amalgam alloy particles and mercury. Factors such as the proportion of amalgam alloy to mercury and trituration/condensation procedures can affect dimensional change.

Does amalgam expand?

Additionally, “amalgam” fillings can slowly expand over time placing added pressure inside the tooth against the walls of the filling. This phenomenon is called “creep and flow” – like the filling is getting bigger over time.

What is lathe alignment test?

Geometric lathe alignment tests generally include tests like checking the parallelism of the spindle axis and lathe bed, intersection of headstock and tailstock centers, etc. The main aim of these alignment tests is to check the accuracy of the work done on the machine.

What is setting time of amalgam?

The setting time of amalgam depends on the composition of the alloy, the shape and size of the particle and the mixing time. 90 % of the final hardness will be reached after 10 – 12 hours.

What component of amalgam increases the setting time?

Silver (Ag): Increases Strength, Decreases setting time, tarnishes easily, whitens the alloy, decreases creep, Increases resistance to tarnish, increases the expansion on setting.

What is admixed alloy?

Admixed alloy powder:  Also called as blended alloys.  Contain 2 parts by weight of conventional composition lathe cut particles plus one part by weight of spheres of a silver copper eutectic alloy.  Made by mixing particles of silver and tin with particles of silver and copper.

What is lathe cutting?

A lathe (/leɪð/) is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece to create an object with symmetry about that axis.

Can a filling expand?

These undercuts can seriously weaken the tooth. Additionally, “amalgam” fillings can slowly expand over time placing added pressure inside the tooth against the walls of the filling. This phenomenon is called “creep and flow” – like the filling is getting bigger over time.

How do you set up a cutting tool machine?

To setup a Cutting Tool for Machining Mount a toolholder in the toolpost so that the set screw in the toolholder is about 1 inch beyond the toolpost. Insert the proper cutting tool into the toolholder, having the tool extend .500 inch beyond the toolholder. Set the cutting tool point to center height.

What is the setting time?

Setting time is the time required for stiffening of cement paste to a defined consistency. Indirectly related to the initial chemical reaction of cement with water to form aluminum-silicate compound.