YY/T 1702-2020Dentistry—Additive manufacturing—Selective laser melting metallic materials for fixed and removable restorations and appliances (English PDF)

3.4 Y-axis

The axis that is perpendicular to the x-axis and z-axis in the coordinate system of the equipment.

NOTE 1: Unless otherwise specified by the equipment manufacturer, it usually refers to the y-axis of the equipment.

NOTE 2: Except as specified by the equipment manufacturer, the definition of positive direction of the y-axis follows the right-hand rule of the coordinate system in GB/T 19660. Usually, when the z-axis is positively upwards, at this time, when viewing from the front side of the equipment, the direction from the front to the back of the equipment is the positive direction of the y-axis.

When the z-axis is positively downwards, at this time, when viewing from the front side of the equipment, the direction from the back to the front of the equipment is the positive direction of the y-axis.

NOTE 3: Usually the y-axis is in the horizontal position. [GB/T 35351-2017, definition 2.3.21]

3.5 Z-axis

The coordinate axis that is perpendicular to the x-axis and y-axis (the plane formed by them) in coordinate system of the equipment.

NOTE 1: Unless otherwise specified by the equipment manufacturer, it usually refers to the z-axis of the equipment.

NOTE 2: Except as specified by the equipment manufacturer, the definition of the positive direction of z-axis follows the right-hand rule of the coordinate system in GB/T 19660. For a process that uses planes and materials to superimpose layer by layer, the normal direction of the layer is the positive direction of the z-axis. For the process that uses planes and materials to superimpose layer by layer, the positive direction of z-axis points from the first layer to the subsequent layer.

NOTE 3: When materials are superimposed from different directions [e.g.: in a directional energy deposition system], the z-axis may be determined according to rotation or rolling in GB/T 19660. snap rings.

5.1 Metal powder

5.1.9 Solidus and liquidus temperature (alloy) or melting point (commercial pure metal)

5.1.10 Package accompanying documents, instructions manual, marking and See introduction.

5.1.1 Chemical composition

Test according to 8.1.1, it shall comply with the provisions of 5.1 in ISO 22674-2016.

5.1.2 Hazardous ingredients

Test according to 8.1.1, it shall comply with the provisions of 5.2 in ISO 22674-2016.

5.1.3 Powder appearance

Test according to 8.1.2, the powder is even, and there are no visible impurities.

5.1.4 Roundness

Test according to 8.1.3, the roundness shall be no less than the claimed value of the manufacturer.

5.1.5 Powder size and distribution

Test according to 8.1.4, D10>=12µm; D90<=65µm.

5.1.6 Powder flowability

Test according to 8.1.5, cobalt-chromium alloy powder: no more than 40s/50g; titanium and titanium-alloy powder: no more than 50s/50g.

5.1.7 Bulk density of powder

Test according to 8.1.6, cobalt-chromium alloy powder: no less than 4.0g/cm³; titanium and titanium alloy powder: no less than 2.2g/cm³.

5.1.8 Tap density of powder

Test according to 8.1.7, cobalt-chromium alloy powder: no less than 4.5g/cm³; titanium and titanium alloy powder: no less than 2.5g/cm³.

Test according to 8.1.8, it shall meet the requirements of 5.9 in ISO 22674-2016.

7.1 Overview

Prepare all samples in accordance with the documents attached to the product package (see 9.1) and the manufacturer's instruction manual (see 9.2).

The effect of printing direction on performance shall be fully considered. For the tensile performance, bending performance, corrosion resistance, anti-tarnish performance, linear expansion coefficient and metal-porcelain system performance, two sets of samples shall be prepared; that is, the long axis of the sample is parallel to the printing growth direction (z-axis direction) and the long axis of the sample is perpendicular to the printing growth direction (x-axis or y-axis direction). The performances of the two sets of specimens in the two printing directions shall both meet the requirements of the corresponding clauses. Replace all samples with visible defects.

The sample preparer shall provide relevant information and main printing parameters (including at least: laser power, scanning speed, printing distance, spot diameter, and powder layer thickness) of the used printing equipment.

The relevant information and main printing parameters of the printing equipment provided by the manufacturer shall be confirmed; and the printed product performance shall meet all the requirements of this Standard. If the printing equipment and main printing parameters are changed, the printed product performance shall be reconfirmed according to 5.2.

7.2 Heat treatment

7.2.1 Metal materials

recommended for heat treatment in the manufacturer's instruction manual If the manufacturer recommends heat treatment [9.2c)], the heat treatment shall be carried out in accordance with the heat treatment conditions specified in the manufacturer's instruction manual, including for stress relief heat treatment and softening and hardening heat treatment, etc.

7.2.2 Metal materials for metal-porcelain restorations

It shall be carried out according to the provisions of 7.2.3 in ISO 22674-2016.

7.3 Specimen

The number of samples in this part does not include the metal materials that are used for metal-porcelain restorations. If the product is used for metal-porcelain restorations, the number of samples shall be doubled, and sample processing shall be carried out according to 7.2.2.

7.3.1 Surface roughness, hardness, density, inclusions and porosity

Prepare a cube sample with a side length of at least 10mm (e.g. 10mm×10mm×10mm) according to the manufacturer's instruction manual; mark and print the positive direction of z-axis on the surface of the specimen (see 3.5); and perform heat treatment in accordance with 7.2.1; and prepare 6 specimens.

The above 4 tests share 1 set of specimens. The specimen shall maintain the original printed surface, and shall not be subjected to any metal processing such as grinding or turning, etc.

7.3.2 Dimension and warpage deformation

A single-sided cantilever beam specimen with a thickness of 1mm is used and prepared according to the size in Figure 1. The shape of the support is designed by the manufacturer and is consistent with the actual production process.

After printing is completed, perform heat treatment according to 7.2.1. Prepare 5 specimens.

Prepare the specimen with size of (25±2)mm × (2.0±0.1)mm × (2.0±0.1)mm according to the manufacturer's instruction manual; respectively prepare 6 specimens with the long axis of the specimen parallel to the printing growth direction (z-axis direction) and with the long axis of the specimen perpendicular to the printing growth direction (x-axis or y-axis direction). Perform heat treatment on the specimen according to 7.2.1.

7.3.4 Corrosion resistance

Prepare sample in accordance with 7.7 in ISO 22674-2016. Respectively prepare 2 specimens with the long axis of the specimen parallel to the printing growth direction (z-axis direction) and the long axis of the specimen perpendicular to the printing growth direction (x-axis or y-axis direction). Perform the heat treatment on the specimens according to 7.2.1.

7.3.5 Anti-tarnish

Prepare sample in accordance with 7.8 in ISO 22674-2016. Respectively prepare 2 specimens with the long axis of the specimen parallel to the printing growth direction (z-axis direction) and the long axis of the specimen perpendicular to the printing growth direction (x-axis or y-axis direction). Perform the heat treatment on the specimens according to 7.2.1.

7.3.6 Linear thermal expansion

Prepare sample in accordance with 7.9 in ISO 22674-2016. Respectively prepare 2 specimens with the long axis of the specimen parallel to the printing growth direction (z-axis direction) and the long axis of the specimen perpendicular to the printing growth direction (x-axis or y-axis direction). Perform the heat treatment on the specimens according to 7.2.1.

7.3.7 Performance of metal-porcelain system - peel/crack initiation strength

Prepare sample in accordance with the provisions of 6.4.2 in YY 0621.1-2016.

Respectively prepare 6 specimens with the long axis of the specimen parallel to the printing growth direction (z-axis direction) and with the long axis of the specimen perpendicular to the printing growth direction (x-axis or y-axis direction). Perform heat treatment on the specimen according to 7.2.1.

8.1 Metal powder

8.1.9 Package accompanying documents, instruction manual, markings and labels Check whether it meets the requirements of Clauses 9 and 10.

8.1.1 Chemical composition and hazardous ingredients

Test according to 8.2 in ISO 22674-2016, it shall comply with the provisions of 5.1.1 and 5.1.2. provisions of 5.1.9.

8.2 Printout

In the test process of surface roughness, hardness, density, inclusions and porosity, in order to avoid the economic burden on the sample preparer due to repeated sample preparation, the same set of samples may be used for multi-item tests. The test sequence is to conduct surface roughness test first, and then to test hardness, density, inclusions and porosity.

8.2.1 Surface roughness

Prepare the sample according to 7.3.1; refer to the positive direction of z-axis marked on the surface of the specimen; and perform the test along the printing growth direction (z-axis). Test in accordance with the provisions of GB/T10610-2009; and measure the Ra value of the measured surface. All 6 specimens shall comply with the provisions of 5.2.1.

8.2.2 Dimensions

Measure by measuring instruments with an accuracy of at least 0.01mm.

Measure the thickness of the specimen prepared in accordance with 7.3.2; and the deviation of the thickness of the 5 specimens from the design dimensions shall meet the requirements of 5.2.2.

8.2.3 Warpage deformation

Prepare the sample according to 7.3.2; and perform heat treatment according to 7.2.1.

Measure the height of the upper surface of the specimen at point A on the centerline (as shown in Figure 2, the farthest end of the cantilever beam), that is, the distance between point A on the upper surface of the specimen and the substrate. Pressure cannot be applied to the sample during the measurement. It is recommended to choose a non-contact measuring instrument, accurate to 0.01mm.

Then, truncate the 55mm support of the specimen, leaving only the fixed end of 10mm connected to the substrate (or specimen printing base plate), so that the specimen is in a cantilever beam state (see Figure 2).

NOTE 1: The height position of the truncated support is not required. The truncation process shall ensure the integrity of the specimen. d - support truncated position; A - Measurement position of warpage deformation.

NOTE 1: The allowable error is ±0.5mm.

Figure 2 -- Warpage Deformation Test

8.2.4 Mechanical properties

8.2.4.1 Hardness

The 6 specimens, after completing the test in accordance with 8.2.1, refer to the positive direction of z-axis indicated on the surface of the specimen, respectively select a test surface with the long axis of the specimen parallel to the printing growth direction (z-axis direction) and the long axis of the specimen perpendicular to the printing growth direction (x-axis or y-axis direction); Polish the selected test surfaces according to the procedures specified in GB/T 13298. Test in accordance with the provisions of GB/T 4340.1-2009.

Tests are carried out on the two test surfaces of each specimen. All 12 test surfaces of the 6 specimens shall comply with the provisions of 5.2.4.1.

8.2.4.2 Tensile properties

Test according to the provisions of 8.3~8.7 in ISO 22674-2016; it shall meet the requirements of 5.2.4.2.

8.2.4.3 Bending performance

Test according to the provisions of GB/T 3851-2015. The fulcrum distance is 20 mm; and the radius of curvature of the fulcrum and the indenter is 2 mm. The test is carried out at a speed of 1.0 mm/min; record the 0.2% specified non-proportional bending stress of the bending test. The 0.2% specified non-proportional bending stress of the 6 specimens shall meet the requirements of 5.2.4.3.

8.2.5 Inclusions and porosity

The 6 specimens, after completing the hardness test according to 8.2.4.1, shall respectively select 1 test surface with the long axis of the specimen parallel to the printing growth direction (z-axis direction) and the long axis of the specimen perpendicular to the printing growth direction (x-axis or y-axis direction). Test area fraction of looseness, non-metallic inclusions and porosity for sample according to

GB/T 18876.1-2002. The selected field of view shall avoid the position of hardness indentation; and the field of view with more areas of looseness, non-metallic inclusions and pores shall be selected for calculation.

c) The roundness of the powder;

d) Powder size and distribution;

e) The fluidity of the powder;

f) Liquidus and solidus temperature (alloy), or melting point (pure metal);

g) 0.2% specified non-proportional extension strength;

h) Elongation after break;

i) Young's modulus;

j) The product has an anti-tarnish statement (see 5.7), if applicable;

k) Linear expansion coefficient, if the product is used to make metal porcelain restorations;

l) The recommended maximum porcelain temperature, if the product is used to make metal porcelain restorations;

m) Recommended brazing, fusion welding and other connection techniques;

n) Recommended storage conditions;

o) Detailed information about potential side effects and mark "This product contains nickel", if the nickel content in the product exceeds 0.1% (mass fraction).

9.2 Instruction manual

The detailed instruction manual shall be provided to the purchaser by the distributor and manufacturer as a package accompanying document. The specific content shall include:

a) Recommendations and information on forming and processing;

b) If metal materials are used to make metal-porcelain restorations, the processing conditions shall be explained, and instructions for satisfactory bonding surface preparation with at least one matching (designated) porcelain material that complies with ISO 9693 shall be provided;

c) The recommended heat treatment process, including stress relief heat treatment and softening and hardening heat treatment;

d) Recommendations to prevent dust inhalation during grinding;

e) The manufacturer shall provide the recommended printing parameters (including at least: laser power, scanning speed, printing distance, spot diameter and