Three-dimensional (3-D) object printers, such as those which employ Fusion Deposition Modeling (FDM), are known. The printing process for such a device involves the deposition of printing material onto a printing platform, also referred to as a print bed. The deposited material may be melted into a pliable state, extruded through a heated nozzle and built up, layer by layer, until the final result is a 3-D object. Because the layers are deposited in sequence on top of each other, print success and quality depend upon the ability to maintain registration of the object with the extruder nozzle throughout the duration of the print job to ensure that each stacked layer registers with the previous one.
Print success and quality may also depend upon adequate adhesion between the printed object and the print bed. Sometimes the first few layers of the printed object do not have sufficient adherence to the print bed, causing the printed object to shift, warp, or delaminate from the print bed, resulting in a failed or poor quality printed object. The print beds for known FDM style 3-D printers are typically made of metal, glass or acrylic. These print beds are not considered consumables, nor are they ideally suited to provide reliable surfaces on which the 3-D printed objects can adhere solidly and consistently. Therefore, it is preferable to pretreat and/or cover the print bed surface of a FDM style 3-D printer prior to printing an object so as to prevent damaging the print bed and to improve the likelihood that the printed object will adhere adequately to the print bed for the duration of the print.
Manufacturers and users of FDM style 3-D printers often require or recommend covering the print bed surface with heat resistant polyimide film or paper masking tape (typically used by painters), and/or pre-treating the surface with hairspray, special water-soluble glue or other liquid treatment solutions. These applications are intended to hold the 3-D printed object to the surface while it is printing and to preserve the longevity of the original print bed. These print bed covering materials are intended to provide a removable and replaceable surface on which to print, and in some cases take the wear and tear that would otherwise be inflicted upon the print bed.
Printer manufacturers may also recommend using a heated print bed for 3-D printing deposit material that requires slower cooling time, such as ABS (acrylonitrile butadiene styrene). Often times the heated print bed is heated to temperature up to 100-130 degrees Celsius. In such cases, the print bed cover material must be able to function while be exposed to the elevated temperature of the print bed. Accordingly, heat resistant polyimide films may be used for heated print beds, while paper masking tape cannot. Other types of deposit material, such as PLA (polylactide), are not slow cooling and do not require a heat tolerant covering material, such as paper masking tape. In general these two common alternatives (heat resistant polyimide films and paper masking tapes) cannot be used interchangeably with different deposit materials due to their differing properties and heat resistant limitations. Thus, there is a need for a single type of print bed cover which may be used with both heated and non-heated print beds.
Further, there are number of disadvantages that may arise from using known print bed covers. For example, commonly used heat resistant polyimide films or paper masking tapes may be difficult and tedious to apply or install on the print bed. Polyimide films and paper masking tape generally are supplied on a roll and need to be cut and resized for the print bed on which they are installed. If the width of the supplied roll is not as wide as the print bed, then multiple sheets of the film or tape may need to be applied side by side in order to cover the print bed. However, it is extremely important that the print bed surface be flat and level to the extruder nozzle; i.e., the gap between the extruder nozzle and top surface of the print bed needs to be uniform over the entirety of the print bed. Failure to provide a uniform distance between the extruder and the print bed cover may result in defective print objects and even damage or tearing of the cover if the extruder nozzle contacts it. Therefore, for best 3-D printing results, the films and tapes need to be applied without overlapping seams, folds, creases or air bubbles under or in the covering surface since such irregularities may cause variation of the distance between the extruder nozzle and the print surface. Because the known films and tapes are typically very thin, they are difficult to work with in a manner that avoids overlapping and air bubbles, and are susceptible to unwanted stretching, folding and creasing while being adhered to the print bed.
Another difficulty which arises from using polyimide film or paper masking tape is that they may not provide sufficient adhesion to keep the 3-D printed object from moving or warping upward during the printing process, resulting in a failed or defective printed object. Alternatively, in some instances, polyimide film or paper masking tape provide so much adhesion that upon completion, the 3-D printed object is difficult to remove from the print surface, which can result in damage to the print bed cover or printing device, or even in personal injury. Excessive adhesion may be further complicated by the thinness of the polyimide film and paper masking tape. When adhesion is too great, the film or tape may be damaged when the printed object is removed from it, or when leftover deposited material is scraped off. The foregoing challenges may result in the need for frequent replacement of the polyimide film or paper masking tape.
Water-soluble glue is another known covering material for 3-D printer beds. The use of such glues, however, requires exposing the completed 3-D printed object to water while it is still adhered to the print surface (through various methods) in order to separate the 3-D printed object from the print surface. This water application step can be inefficient since (a) it is an extra step that would not otherwise be required, (b) requires a new application of glue for each printing operation, and (c) may not work in many situations where the original print bed is equipped with an FDM style 3-D printer bed that is not easily removable from the printing device. Extremely rigid perfboard or FR4 fiberglass (which is typically used to make printed circuit boards) are still other covering materials that are currently used as print surfaces or covers. Such materials may also suffer from removal problems.