This disclosure describes multi-fluid kits for three-dimensional printing, three-dimensional printing kits, and methods of sensing metal ions using three-dimensional printed ion sensors. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent and an ion-sensing agent. The fusing agent can include water and an electromagnetic radiation absorber. The electromagnetic radiation absorber can absorb radiation energy and convert the radiation energy to heat. The ion-sensing agent can include water and a redox-active inorganic salt.

The present disclosure describes three-dimensional printing with scent agents. In one example, a multi-fluid kit for three-dimensional printing can include a fusing agent comprising water and a radiation absorber, wherein the radiation absorber absorbs radiation energy and converts the radiation energy to heat; and a scent agent comprising a scented compound dissolved in an aqueous liquid vehicle that includes water and organic co-solvent, wherein the organic co-solvent includes an aliphatic polyol, an esterified aliphatic polyol, or a combination thereof.

A three-dimensional (3D) printed object is described. The 3D printed object comprises a polymer. A surface of the 3D printed object comprises the polymer 5 and a UV absorbing colorant. The surface has a surface area roughness Sa (arithmetical mean height) of ≤5.0 μm. A method for preparing a three dimensional (3D) printed object having a smooth surface is also described.

A molded body, comprising a resin and cells, the cells having an average diameter of from 0.03 mm to 0.13 mm, and a number per unit area of the cells at a cross-section of the molded body being no less than 20 cells/mm.sup.2.

A method and/or a machine is for tabbing a free end on a roll of sheet material. Converting a master roll of sheet material to the roll of sheet material and winding a first roll of sheet material onto a spindle at a winding position. Tabbing the free end of the roll of sheet material at a tabbing position. Where a tabber carrying a joiner are both in an initial position away from the first roll of sheet material, moving the tabber to a second position adjacent the roll of sheet material, moving the joiner into an engagement position where the joiner is engaged with the free end of the roll of sheet material. The joiner creates a tab with a combination of mechanical entanglement and heat welding. Returning the tabber and joiner to the initial positions. Doffing the tabbed roll of sheet material. The roll produced by the foregoing.

A method and/or a machine is for tabbing a free end on a roll of sheet material. Converting a master roll of sheet material to the roll of sheet material and winding a first roll of sheet material onto a spindle at a winding position. Tabbing the free end of the roll of sheet material at a tabbing position. Where a tabber carrying a joiner are both in an initial position away from the first roll of sheet material, moving the tabber to a second position adjacent the roll of sheet material, moving the joiner into an engagement position where the joiner is engaged with the free end of the roll of sheet material. The joiner creates a tab with a combination of mechanical entanglement and heat welding. Returning the tabber and joiner to the initial positions. Doffing the tabbed roll of sheet material. The roll produced by the foregoing.

A hollow molded article having a joining site where two or more split objects are welded by plastic welding and comes into contact with pressurized hydrogen, wherein an average spherulite size in a portion which is 500 μm deep inside from a surface of the hollow molded article is 20 μm or less, and a tensile strength of a test piece containing the joining site of the hollow molded article is 80% or more based on a tensile strength of a test piece not containing the joining site of the hollow molded article.

A hollow molded article having a joining site where two or more split objects are welded by plastic welding and comes into contact with pressurized hydrogen, wherein an average spherulite size in a portion which is 500 μm deep inside from a surface of the hollow molded article is 20 μm or less, and a tensile strength of a test piece containing the joining site of the hollow molded article is 80% or more based on a tensile strength of a test piece not containing the joining site of the hollow molded article.

A method of bonding a first object to a second object includes the steps of: providing the first object including thermoplastic material in a solid state, providing the second object including a proximal surface, applying a mechanical pressing force and a mechanical excitation capable to liquefy the thermoplastic material until a flow portion of the thermoplastic material is flowable and penetrates into structures of the second object, and stopping the mechanical excitation and letting the thermoplastic material resolidify to yield a positive-fit connection between the first and the second object. The second object has a region of low density, wherein the protrusion penetrates the region of low density at least partly before the thermoplastic material is made flowable, and wherein the first object includes a protruding portion after the step of letting the thermoplastic material resolidify, the protruding portion at least partly penetrates the region of low density.

A method of bonding a first object to a second object includes the steps of: providing the first object including thermoplastic material in a solid state, providing the second object including a proximal surface, applying a mechanical pressing force and a mechanical excitation capable to liquefy the thermoplastic material until a flow portion of the thermoplastic material is flowable and penetrates into structures of the second object, and stopping the mechanical excitation and letting the thermoplastic material resolidify to yield a positive-fit connection between the first and the second object. The second object has a region of low density, wherein the protrusion penetrates the region of low density at least partly before the thermoplastic material is made flowable, and wherein the first object includes a protruding portion after the step of letting the thermoplastic material resolidify, the protruding portion at least partly penetrates the region of low density.