First Download eloquent-sluggable package for laravel 5.5

composer require cviebrock/eloquent-sluggable:^4.3

added following code in model

# importing
use Cviebrock\EloquentSluggable\Sluggable;
# method
public function sluggable()
{
    return [
        'slug' => [
            'source' => 'name'
        ]
    ];
}

inside seeder class

#importing
use Cviebrock\EloquentSluggable\Services\SlugService;
use Cviebrock\EloquentSluggable\Sluggable;
use Sluggable;

public function sluggable()
{
    return [
        'slug' => [
            'source' => 'name'
        ]
    ];
}

# using SlugService
'slug' => SlugService::createSlug(Hospital::class, 'slug', $company),