WO2021150248A1

WO2021150248A1 - Energy source setting

Info

Publication number: WO2021150248A1
Application number: PCT/US2020/015069
Authority: WO
Inventors: Pol FORNOS MARTINEZ; Maria de las Mercedes BLANCO ROLLAN; Theodore ROBINSON
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-01-24
Filing date: 2020-01-24
Publication date: 2021-07-29

Abstract

A method comprising initiating a test build in an additive manufacturing system. The test build comprises building a plurality of test objects. Each test object comprises an object portion of a plurality of adjacent layers of build material. The object portion of each layer is solidified as a result of irradiation by a variable output energy source which is set to provide a consistent amount energy per unit area for each object portion of a test object and to provide a different amount of energy per unit area for each test object. During building of each test object the temperature of a region of the object portion of a set of the plurality of adjacent layers is measured and a trend in the measured temperature is determined for each test object. Based on the temperature trends determined a setting for the variable energy source to be used for a subsequent build in the additive manufacturing system is determined.

Description

Energy Source Setting

[0001] Additive manufacturing systems can be used to manufacture three-dimensional (3D) objects. This can be achieved, for example, by forming successive layers of a build material on a build platform and selectively solidifying portions of those layers to build up a 3D object. Objects such as product components can be built up in layers in an additive manufacturing system in accordance with object descriptions as part of a build instruction that are interpreted and applied by a print controller.

[0002] In an example additive manufacturing process using printer control fluids, a fusing agent (FA) fluid can be used to promote a build powder’s absorption of energy from an energy source, to promote heating, melting, and fusing of the build powder, and a detailing agent (DA) fluid can be used adjacent to the fusing agent fluid to inhibit unwanted fusing of adjacent powder, or to cool regions where FA is applied. The FA has the effect of raising the temperature of the build powder when irradiated by an energy source, and the DA has the effect of reducing the heating effect of this radiation on build powder that it is applied to, providing highly localised control of powder fusing.

[0003] Examples of the present disclosure will now be described with reference to the accompanying Figures, in which:

[0004] Figure 1 shows a schematic view of an example of an additive manufacturing system;

[0005] Figure 2 shows a schematic cross section view of the additive manufacturing system of Figure 1 according to an example;

[0006] Figure 3 shows a flow chart for an example of a method;

[0007] Figure 4 shows a graph of layer number against temperature;

[0008] Figure 5 shows the graph of Figure 4 with temperature trends marked;

[0009] Figure 6 flow chart for another example of a method; and [0010] Figure 7 shows a schematic diagram of an example of a controller.

[0011] Some additive manufacturing systems use build material which is spread over a build platform to form a build layer. Selected portions of the build layer may be solidified, for example by fusing, sintering, melting, binding or otherwise joining the build material using, for example, heat energy applied from an energy source and a fusing agent. The build platform may then be lowered by a predetermined amount and a new build layer may be formed on the previously formed layer and the process repeated. In this way solid objects can be created.

[0012] The build material may comprise any suitable form of build material, for example fibres, granules or powders. The build material can include thermoplastic materials, ceramic material and metallic materials. A store of build material may be provided in a supply vessel and build material may be distributed from the supply vessel to form an intermediate volume of build material from which build material may be spread over a build platform, either directly such as using a roller to spread the intermediate volume, or indirectly by moving some or all of the intermediate volume to another location prior to spreading. [0013] Figure 1 shows a schematic view of an additive manufacturing system 1 . The additive manufacturing system 1 comprises a build unit 2 which, in this example, includes two feed trays 4. The feed trays 4 are arranged on opposite sides of a build platform 6, and build material is distributed to the feed trays 4 from a build material store 8 within the build unit 2. In this example the build material store 8 is shown in dotted lines within the build unit 2.

[0014] The additive manufacturing system 1 includes a recoater 10 which spreads build material across the build platform 6, or a previous build layer, to form a new build layer. In this example the material to be spread is from a feed tray 4 at a side of the build platform 6, but in other examples the powder may come from other sources. The recoater 10 in this example comprises a spreader having a roller which engages a volume of build material to be spread. In other examples spreaders may include a blade, a brush or a roller, or combinations of these, and / or other suitable devices. The volume of build material to be spread may be a ridge of build material lifted from the volume of build material in a feed tray 4 by a feed vane 12.

[0015] The recoater 10 is controlled to move over the build platform 6 in a first direction 14 to spread a build layer of build material. In this example the build layer is substantially planar. Once a build layer has been formed a carriage 16 is moved over the build platform 6 to selectively solidify portions of the build layer. The carriage 16 in this example moves in a second direction 18 which is substantially perpendicular to the first direction 14, although this may not be the case in all examples. The carriage 16 includes thermal sensors 32 which will be described in more detail with reference to Figure 2. The additive manufacturing system is controlled by a controller 78 which will be described in more detail with reference to Figure 7.

[0016] In the example of the additive manufacturing system 1 as shown in Figure 1 the build unit 2 is provided as a removable build unit which can be removed from a printer unit which comprises the recoater 10 and carriage 16. In other examples the build unit may be integrally formed with a printer unit, and/or other parts of an additive manufacturing apparatus.

[0017] Figure 2 shows a schematic cross section view of the additive manufacturing system 1 of Figure 1. The additive manufacturing system 1 is depicted during a test build operation and the vane 12 has lifted a ridge 18 of build material from a feed tray 4 on one side of the build platform 6 to allow a roller 20 of the recoater 10 to create a new build layer over the previous build layer. As shown, the build platform 6 has been incrementally lowered to allow the new build layer to be created by the recoater 10. The thickness of the build layer can be varied as desired and may depend upon a variety of factors including complexity of object to be created the speed of build desired and the resolution of the object desired.

[0018] Once a new build layer has been created the carriage 16 will move across the build layer to selectively solidify portions of the build layer. The carriage 16 in this example includes dispensers 22 which dispense fusing and/or detailing agent onto selected portions of the build layer, and a variable energy source, in this example a fusing lamp 24, which provides energy to the build layer as the carriage 16 moves over the build layer. An example of a suitable fusing lamp 24 is an infra-red lamp, which may comprise a halogen bulb.

[0019] The combination of fusing and/or detailing agent and the energy provided by the variable energy source result in the selective solidification of portions of the build layer, these selectively solidified portions will be referred to as object portions. Although a fusing lamp 24 is used in this example, in other examples a plurality of fusing lamps 24 could be used.

[0020] In other examples any suitable variable energy source can be used to provide energy to a build layer to create the object portions, and these could include lasers, lamps, microwaves, or combinations of these or other sources in which the energy per unit area applied to build layers during a build operation can be altered. This may be achieved by adjusting the length of time for which energy is applied to a build layer, portions of a build layer, or by adjusting the power output of the variable energy source, or a combination of these.

[0021] The variable energy source is variable so that the energy that it applies to a build layer can be altered, for example changing the energy per unit area applied to the build layer. This altering of the energy applied to a build layer may be achieved by changing the power output of the variable energy source, and/or may be achieved by altering the time for which the energy is applied.

[0022] In one example the carriage 16 moves across every build layer at a substantially constant rate which means that the time for which energy is applied to each region of every build layer is substantially constant. The variability of the energy applied in this example is achieved by varying the power output of the fuse lamp 24. In this example the power output of the fuse lamp 24 is not changed as the carriage moves over a build layer, but can be changed between layers. Thus the energy applied across a build layer is substantially constant, but may be changed between build layers.

[0023] In other examples the energy that the variable energy source applies to a build layer can be altered across a layer, for example as the carriage moves over the build layer. The variable energy source could be moved at a variable speed over the build layer while emitting a constant power output, thus altering the energy supplied per unit area per carriage pass. Also, or alternatively, the power output of the variable energy source may be varied, for example by altering the intensity of the output. [0024] Following the selective solidification of portions of the build layer the build platform 6 is lowered and the process repeated for the build to be completed. In this example a build chamber 26 above the build platform 6 has been created by the incremental lowering of the build platform 6 during the build operation and the build chamber 26 contains a plurality of build layer, two test objects 28 and a partly completed test object 30. The object portions of several sets of adjacent build layers which overlie one another and have been solidified together to create each of the test objects 28. In this example, the sets of adjacent build layers that form each of the test objects 28 and partly completed test object 30 do not overlap, and the sets of layers that form the test objects 28 and partly completed test object 30 are separated by gaps comprising a plurality of layers. In this example the power output of the energy source is the same for each of the set of layers forming a test object, and is different for each test object.

[0025] In this example the carriage also includes thermal sensors 32 which can measure, for example during building, the temperature of a region 34 of an object portion of the most recently created build layer. A single thermal sensor 32 can be used, or there may be a plurality of thermal sensors 32. A thermal sensor 32 may be mounted in the carriage as shown in this example, but a thermal sensor could be mounted anywhere, static or movable, from which it can measure the temperature of the appropriate region. An example of a suitable temperature sensor is a thermal camera.

[0026] The additive manufacturing system 1 includes a controller 78 which includes instructions executable by the additive manufacturing system to carry out a method. The controller 78 will be discussed in more detail with reference to Figure 7.

[0027] Figure 3 shows a method 36 comprising initiating 38 a test build in an additive manufacturing system, for example the additive manufacturing system 1 of Figure 1. The test build comprises building 40 a plurality of test objects. In one example all of the test objects are substantially identical and each of the test objects is formed in a non-overlapping sets of build layers. In other examples the test objects may not be identical and may be formed in at least partially overlapping sets of build layers. The test objects may be any shape, for example they may have a cross section perpendicular to the layers which is a regular shape such as square or circular, or they may have an irregularly shaped cross section. The test objects specified in the test build may have a substantially constant area in a plane parallel to a plane of the build layers. Each test object may, for example, comprise 50 layers, 70 layers, or 100 layers of build material. The number of layers may depend upon the thickness of the build layers from which the object is built. The build layer thickness may be substantially consistent during a test build.

[0028] In this example the test build specifies that the test objects are be spaced apart from one another by gaps which are perpendicular to the plane of the build layers so that the test objects comprise object portions formed in non-overlapping sets of build layers. The gaps may comprise a plurality of layers of build material in which no portion is solidified. The gaps may comprise, for example, 20 layers, 50 layers, or 100 layers of build material. The number of layers in the gaps may depend upon the thickness of the build layers. In other examples the gaps may be parallel to the plane of the layers of build material. The gaps may assist in thermally separating the test objects from one another.

[0029] The test build is a build operation in which the additive manufacturing system is controlled to carry out a test build to produce a plurality test objects. The test objects have intended dimensions, but the actual dimensions of the test objects produced may differ from the intended dimensions due to, for example thermal bleed or contraction. In some examples the test build operation may be terminated before all of the plurality of test objects specified in the test build have completed.

[0030] In this example, each test object comprises an object portion of a nonoverlapping set of a plurality of adjacent layers of build material in the additive manufacturing system. The object portion of each layer is solidified as a result of irradiation by a variable output energy source, for example the fusing lamp 24 of the additive manufacturing system 1 of Figures 1 and 2. In this example the variable energy source is set to provide a constant power output across each build layer, to provide the same constant power output across each build layer of a test object and to provide a different power output for each test object. In one example the variability of the energy source comprises using one of a plurality of pre-set, or predetermined, power output levels for the energy source between a lowest and a highest. In other example the power output may be substantially continuously variable.

[0031]The method 36 comprises measuring, for example by measuring using the sensors 32 of the additive manufacturing system 1 of Figure 1 , during building of each test object, the temperature of a region of the object portion of a set of the plurality of adjacent layers which form the test object. The set of the plurality of adjacent layers may comprise all the build layers that make up the test object, the set may comprise a random sample of some of the build layers, or may comprise a predetermined subset of the adjacent layers, for example every other layer, or every fifth layer. The set of the plurality of adjacent layers may exclude an initial plurality of layers. For example the initial 10 to 20 layers in which object portions are solidified at the start of the creation of a test object may be excluded as there may be transient temperature effects that may hinder later analysis of the temperature results.

[0032] The temperature of a region of the object portion may be measured at a consistent stage in the build process for each layer, for example the temperature may be measured immediately prior to a recoating operation being carried out by the additive manufacturing system. This is a stage at which a direct measurement of the temperature of the object portion can be obtained as the object portion has not yet been covered in a new layer of build material.

[0033] The method 36 further comprises determining 42 during building of each test object, based on the measured temperatures of layers in the object portion, a trend in the measured temperature of the region of the object portion in a test object. The method comprises determining 44, based on the temperature trend determined, a setting for the variable energy source to be used for a subsequent build in the additive manufacturing system.

[0034] An object being built in an additive manufacturing system , for example that of Figure 1 , based upon build instructions which specify the dimensional of an object to be built, may experience a phenomenon known as thermal bleed. [0035] An object which has experienced thermal bleed has build material adhered to the object which was not identified in the build instructions. This can happen when build material surrounding an object is affected by diffusion of heat energy from an object being built and adheres to that object. The amount of energy applied to the object by the variable energy source has a direct impact on amount of energy absorbed by the object and thus the temperature of the object, and on the amount of energy that diffuses from the object. The amount of energy diffused by the object may depend upon the build material being used, the additive manufacturing apparatus and the fusing and detailing agent used.

[0036] It has been found that an increasing, or upward, temperature trend in the object portion of layers of an object being built within an additive manufacturing system can result in a greater risk of thermal bleed for an object being built. [0037] As set out above, the temperature trend in the object portion during an additive manufacturing build process depends upon the energy provided to the object portion by the energy source. If it is determined that there is an upward temperature trend in the object portions of subsequent layers during a build then a reduction in the energy applied per unit area of the object portion of a build layer by the energy source for a subsequent build can reduce the rate of, or prevent, an upward trend in the temperature.

[0038] It should be noted that the material properties of the object being built will also depend upon the energy applied per unit area of the object portion of a build layer by the energy source. Material properties may be adversely affected if too little energy is applied. The additive manufacturing system may be set so that the energy source applies a substantially constant, preset, energy per unit area of the object portion of a build layer during the building of an object in a non-test build. However, it can be difficult, or at least time consuming, for a user to determine which setting for the energy source should be used, for example, for a particular combination of additive manufacturing apparatus, fusing and detailing agents and build material.

[0039] As set out above, the test build initiated in the method includes building 40 a plurality of test objects, and the variable energy source is set to provide a consistent amount energy per unit area for each object portion of a test object and to provide a different amount of energy per unit area for each test object. In one example, for each object portion of a build layer of a first test object, the variable energy source is set to a first power output, and for a for each object portion of a build layer of a second or subsequent test object, the variable energy source is set to a second or subsequent power output which differs from previous power settings.

[0040] During the building of each test object the temperature of a region of the object portion of a set of the plurality of adjacent layers which create the test object is measured and a temperature trend is determined. As noted above the temperature trend may depend upon the energy per unit area provided by the variable energy source.

[0041] Figure 4 shows a graph 46 of layer number against temperature for a test build comprising six test objects. In this example the temperature of a portion of every layer has been measured, including those which do not form part of the test objects. In one example the temperature of build layers not forming part of a test object is measured in a region which substantially corresponds with the region of the object portion in which the temperature is measured in layers forming part of the test objects.

[0042] The graph of Figure 4 shows temperature in °C on the vertical axis and layer number on the horizontal axis. Due to pre-heating of the layers by the additive manufacturing apparatus, the non-object layers are stabilised at about 120°C and the non-overlapping sets of layers which form the test objects can be clearly identified by the increase in temperature to raised peaks 48,50,52,54,56,58 at over about 134°C. The six test objects created during this test build were created with the energy per unit area provided by the variable energy source highest for peak 50 and reducing so that the energy per area for peak 50 > peak 54 > peak 58 > peak 48 > peak 52 > peak 56. [0043] Figure 5 shows the graph 46 of Figure 4 with temperature trends 60 marked.

An upward trend, in which the temperature increases as more layers are added, is steeper for those test objects with a higher energy per unit area input with 50 being steepest and 56 being substantially flat at about 136°C. [0044] It has been identified that setting the variable energy source at the highest energy per area that produces a temperature trend which is rising below a predetermined threshold, or is substantially flat, in the object portion can be a reliable setting for producing objects which do not exhibit thermal bleed, and which do not exhibit low energy material property fluctuations. It is therefore possible, once temperature trends have been determined for the test objects, to determine a setting for the variable energy source to a level suitable for use in future non-test builds in the additive manufacturing system based upon those trends and the setting used to produce the associated test objects. The setting determined may be indicated to a user using any suitable indicator, for example visually, using lights, or a graphical user interface, audibly using a speaker, or in any other suitable manner. This indication allows a user to manually set the variable energy source appropriately, or choose to use a higher or lower setting if desired. The variable energy source may be automatically set to the setting determined as this may be easier for a user. The user may have the option of overriding the automatic setting of the variable energy source.

[0045] By carrying out this trend analysis it is possible to set the variable energy source appropriately without the need to wait several hours, or even days, for the object to cool and be cleaned before the object can be analysed to determine whether it exhibits thermal bleed. By carrying out a test build in which multiple test objects are built using different settings of a variable energy source it may be possible to determine the variable output energy source for future builds on the basis of the analysis of the temperature trends in object regions as the test objects are built so that the risk of thermal bleed is eliminated, or at least reduced.

[0046] It should be noted that determining the appropriate setting for the variable energy source needs to be carried out based upon the additive manufacturing system, including any fluids used, the build mode being used and the build material being used, so each time a change is made to the additive manufacturing system, build mode and/or build material being used the variable energy source may need to be reset.

[0047] Figure 6 flow chart for another example of a method 62 which comprises initiating 64 a test build in an additive manufacturing system, for example the additive manufacturing system 1 of Figure 1. The test build is similar to that of the method 36, in that it comprises instructions for building a plurality of test objects, however in the method 62 a test object is built 66 and the temperature trend of the measured temperature of the region of the object portion in a test object is determined 68 and is used to determine whether or not to end 70 the test build at that stage.

[0048] The temperature trend may be indicative that an appropriate setting has been identified for the variable output energy source and so the test build can be halted at that stage. For example, the test build may be stopped if a test object is built in which the temperature trend indicates a temperature increase trend which is below a predetermined threshold, for example less than 1°C per 100 layers, or less than 0.5°C per 100 layers. The test build may be stopped if a test object is built in which the temperature trend indicates that the temperature is substantially stable and not increasing. Stopping the test build once a suitable setting has been identified can significantly shorten the time required to identify a suitable setting. Stopping the test build early may not be suitable if the test build is being carried out with the variable energy source being set at random levels, rather than gradually decreasing, as a higher energy setting which still produces an upward temperature trend below a predetermined threshold, or a level trend. The test build may be ended when the test build is complete and all test objects have been built.

[0049] The test build of the method may start using a highest energy setting of the variable output energy source in which a highest energy per unit area is applied to each build layer to create the first test object. Second and subsequent test objects may be built using sequentially lower energy settings until a lowest energy setting is used for the final test object of the test build. As mentioned above, it has been found that the highest energy setting that provides a temperature trend which meets the required threshold is a suitable setting to reduce risk of thermal bleed and starting with the highest energy and reducing it for each subsequent test object provides an efficient way to identify a suitable setting.

[0050] If the test build is not stopped, and a new test object is to be built, the energy source is set 72 for the building of the new object. The new energy setting may be based on a predetermined sequence of settings, for example from a highest to a lowest in predetermined steps. The new energy setting may be randomly selected from a plurality of predetermined, or calculated, settings that have not yet been used to build a test object during the test build. The new energy setting may be based on the determined temperature trend of the previous test object and the energy setting used for that test object. This may allow the method to not use some energy settings which are unlikely to produce an acceptable temperature trend. For example, based on the tests that produced the graph of Figure 4, following the build of the second test object which resulted in the peak 50 it may have been possible to determine from the gradient of the temperature trend that the energy settings that generated the peaks 54 and 58, although lower than that used for peak 50, are unlikely to produce a test object with an acceptable temperature trend and can therefore be skipped in the test build. This can allow the identification of a suitable energy setting more rapidly.

[0051] The method 62 repeats the building of a test object until the test build is ended because the test build has completed, or because the test build was ended early.

[0052] A suitable setting for the variable energy source is determined 74 based upon the energy trends determined during the test build. The variable output energy source is then set 76 based upon the determined suitable setting so that it can be used for subsequent build operations.

[0053] Figure 7 shows a schematic diagram of a controller 78. In this example the controller 78 comprises a non-transitory computer-readable storage medium 80 comprising instructions 82 executable by a processor. The machine-readable storage medium 68 comprising:

[0054] Instructions 84 to carry out a test build an additive manufacturing system, for example the additive manufacturing system 1 of Figure 1 , the test build comprising a plurality of test objects. Each test object comprises a plurality of adjacent layers of build material, each layer comprising an object portion which is solidified as a result of irradiation by a variable output energy source and the variable output energy source operating at a different output for each test object.

[0055] Instructions 86 to measure, during building, the temperature of a region of the object portion of a set of the plurality of adjacent layers in each of the test objects. [0056] Instructions 88 to analyse the measured temperatures of regions of the solidified portion.

[0057] Instructions 90 to determine, as a result of the analysis, a setting for the variable energy source to be used for a subsequent build in the additive manufacturing system based on the temperature trends determined.

[0058] The instructions 82 may also comprise setting the variable energy source for subsequent build operations.

Claims

1. A method comprising: initiating a test build in an additive manufacturing system, the test build comprising: building a plurality of test objects, each test object comprising an object portion of a plurality of adjacent layers of build material, the object portion of each layer being solidified as a result of irradiation by a variable output energy source, the variable energy source being set to provide a consistent amount energy per unit area for each object portion of a test object and to provide a different amount of energy per unit area for each test object; measuring, during building of each test object, the temperature of a region of the object portion of a set of the plurality of adjacent layers; determining during building of each test object, based on the measured temperatures of layers in the object portion, a trend in the measured temperature of the region of the object portion in a test object; and determining a setting for the variable energy source to be used for a subsequent build in the additive manufacturing system based on the temperature trends determined.

2. A method as claimed in claim 1, in which the temperature of a region of the object portion is measured immediately prior to a recoating operation being carried out by the additive manufacturing system.

3. A method as claimed in claim 1 , in which the variable output energy source is operable at a plurality of different, predetermined, outputs.

4. A method as claimed in claim 1 , in which the variable output energy source is operated at its highest setting for building the first test object and is operated at a lower setting for a subsequent test object.

5. A method as claimed in claim 1 , in which, based up the based on the measured temperatures of layers in the object portion, a gradient of the trend in the measured temperature of the region of the object portion in a test object is used to determine the energy setting to be used for building the next test object in the test build.

6. A method as claimed in claim 1 , in which the test build is stopped once a test object is built in which the temperature trend indicates an increase below a predetermined threshold.

7. A method as claimed in claim 1 , in which the test build includes gaps between test objects, the gaps comprising a plurality of layers of build material in which no portion is solidified.

8. A method as claimed in claim 1 , in which the test objects each comprise 50 layers of build material.

9. A method as claimed in claim 1, the method comprising setting the output of the variable output energy source to be use for subsequent builds in the additive manufacturing system based on the determined setting.

10. An additive manufacturing system comprising: a variable output energy source to irradiate a layer of build material to selectively solidify a portion of that layer a sensor to measure the temperature of a region of the solidified portion; a controller including instructions executable by the additive manufacturing system to: initiate a test build, the test build comprising a plurality of test objects, each test object comprising an object portion a plurality of adjacent layers of build material, the object portion of each layer being solidified as a result of irradiation by a variable output energy source, the variable energy source being set to provide a consistent amount energy per unit area for each object portion of a test object and to provide a different amount of energy per unit area for each test object; measure, during building, the temperature of a region of the object portion of a set of the plurality of adjacent layers in each of the test objects; and analyse the measured temperatures of regions of the solidified portion and, as a result, determining a setting for the variable energy source to be used for a subsequent build in the additive manufacturing system based on the temperature trends determined.

11. An additive manufacturing system as claimed in claim 10, in which the variable output energy source is a fuse lamp.

12 An additive manufacturing system as claimed in claim 10, in which it is the power output from the energy source which is variable.

13. An additive manufacturing system as claimed in claim 10, in which the sensor is a thermal camera.

14. An additive manufacturing system as claimed in claim 10, in which the output of the energy source for subsequent builds in the additive manufacturing system is automatically set based upon the indication.

15. A non-transitory machine-readable storage medium comprising instructions executable by a processor, the machine-readable storage medium comprising instructions to: carry out a test build using an additive manufacturing system, the test build comprising a plurality of test objects, each test object comprising a plurality of adjacent layers of build material, each layer comprising an object portion which is solidified as a result of irradiation by a variable output energy source and the variable output energy source operating at a consistent amount energy per unit area for each object portion of a test object and at a different output for each test object; measure, during building, the temperature of a region of the object portion of a set of the plurality of adjacent layers in each of the test objects; analyse the measured temperatures of regions of the solidified portion and, as a result, determining a setting for the variable energy source to be used for a subsequent build in the additive manufacturing system based on the temperature trends determined.